Follow-up to feedback from #1286, this change simplifies the connection
handling in the SocketClient and makes the communication via TCP more
robust. It introduces the tcpTimeoutListener to encapsulate accept and
i/o timeout handling as well as connection keep-alive, this type could
likely be upgraded to handle more fine-grained tuning of the tcp stack
(linger, nodelay, etc.) according to the properties we desire. The same
methods should be applied to the RemoteSigner which will be overhauled
when the priv_val_server is fleshed out.

* require private key
* simplify connect logic
* break out conn upgrades to tcpTimeoutListener
* extend test coverage and simplify component setup

Refs #1126

Noticed while investigating
https://github.com/tendermint/tendermint/issues/970

As reported by @zramsay, we'd get the warning
from tendermint/rpc/lib because we were passing in
scheme-less addresses, so by default use "tcp".

Also by default, "node" (nodeAddr) has been set to:
  "tcp://localhost:46657"
instead of the bare:
  "localhost:46657"

This change is just to clean up such warnings as
they spuriously would spook users for a package "lite"
that claims to be secure.

Follow-up to #1255 aligning with the expectation that the external
signing process connects to the node. The SocketClient will block on
start until one connection has been established, support for multiple
signers connected simultaneously is a planned future extension.

* SocketClient accepts connection
* PrivValSocketServer renamed to RemoteSigner
* extend tests

* remove accidental binary

* docs: s/Dummy&dummy/KVStore&kvstore/g

* glide update to abci

* update abci import paths

* dummy begone, hello kvstore

* RequestInitChain needs genesisBytes

* glide update

* expose AuthEnc in the P2P config

if AuthEnc is true, dialed peers must have a node ID in the address and
it must match the persistent pubkey from the secret handshake.

Refs #1157

* fixes after my own review

* fix docs

* fix build failure

```
p2p/pex/pex_reactor_test.go:288:88: cannot use seed.NodeInfo().NetAddress() (type *p2p.NetAddress) as type string in array or slice literal
```

* p2p: introduce peerConn to simplify peer creation

* Introduce `peerConn` containing the known fields of `peer`
* `peer` only created in `sw.addPeer` once handshake is complete and NodeInfo is checked
* Eliminates some mutable variables and makes the code flow better
* Simplifies the `newXxxPeer` funcs
* Use ID instead of PubKey where possible.
        * SetPubKeyFilter -> SetIDFilter
        * nodeInfo.Validate takes ID
        * remove peer.PubKey()

* persistent node ids

* fixes from review

* test: use ip_plus_id.sh more

* fix invalid memory panic during fast_sync test

```
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: panic: runtime error: invalid memory address or nil pointer dereference
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: [signal SIGSEGV: segmentation violation code=0x1 addr=0x20 pc=0x98dd3e]
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]:
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: goroutine 3432 [running]:
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: github.com/tendermint/tendermint/p2p.newOutboundPeerConn(0xc423fd1380, 0xc420933e00, 0x1, 0x1239a60, 0
xc420128c40, 0x2, 0x42caf6, 0xc42001f300, 0xc422831d98, 0xc4227951c0, ...)
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: #011/go/src/github.com/tendermint/tendermint/p2p/peer.go:123 +0x31e
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: github.com/tendermint/tendermint/p2p.(*Switch).addOutboundPeerWithConfig(0xc4200ad040, 0xc423fd1380, 0
xc420933e00, 0xc423f48801, 0x28, 0x2)
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: #011/go/src/github.com/tendermint/tendermint/p2p/switch.go:455 +0x12b
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: github.com/tendermint/tendermint/p2p.(*Switch).DialPeerWithAddress(0xc4200ad040, 0xc423fd1380, 0x1, 0x
0, 0x0)
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: #011/go/src/github.com/tendermint/tendermint/p2p/switch.go:371 +0xdc
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: github.com/tendermint/tendermint/p2p.(*Switch).reconnectToPeer(0xc4200ad040, 0x123e000, 0xc42007bb00)
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: #011/go/src/github.com/tendermint/tendermint/p2p/switch.go:290 +0x25f
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: created by github.com/tendermint/tendermint/p2p.(*Switch).StopPeerForError
2018-02-21T06:30:05Z box887.localdomain docker/local_testnet_4[14907]: #011/go/src/github.com/tendermint/tendermint/p2p/switch.go:256 +0x1b7
```

Following ADDR 008 the node will connect to an external
process to handle signing requests. Operation of the external process is
left to the user.

* introduce alias for PrivValidator interface on socket client
* integrate socket client in node
* structure tests
* remove unnecessary flag

Also, we should allow "main" module to log INFO messages like

```
I[02-07|07:57:25.074] Found private validator                      module=main path=/home/vagrant/.tendermint/config/priv_validator.json
I[02-07|07:57:25.076] Found genesis file                           module=main path=/home/vagrant/.tendermint/config/genesis.json
```

Refs https://github.com/cosmos/gaia/issues/118

**BEFORE**:
```
$ tendermint init

```

**AFTER**:
```
$ tendermint init
I[02-07|07:57:25.074] Found private validator                      module=main path=/home/vagrant/.tendermint/config/priv_validator.json
I[02-07|07:57:25.076] Found genesis file                           module=main path=/home/vagrant/.tendermint/config/genesis.json
```

- we only use seeds if we can’t connect to peers in the addrbook.
- we always connect to nodes given in config/flags

Refs #864

config: test the default file

docs: spiff up config

config: minor fixes & comments

config: simplify test

config; use a seperate config directory, #556

config: update docs & parameterize file paths

config: PR comments

config: use the default object

fix a rebase error

* cmd/tendermint: fix initialization file creation checks

Fixes #989.

The original initialization sequence started to inexplicably
fail
```shell
tendermint unsafe_reset_all
tendermint init
tendermint node --proxy_app=dummy
```

used to fail with
```shell
ERROR: Failed to create node: Couldn't read GenesisDoc file: open
/Users/emmanuelodeke/.tendermint/genesis.json: no such file or directory
```

because the initialization sequence always assumed that the
genesisDoc would only be set if the privValidator was generated.

However, `tendermint unsafe_reset_all` only created the
`priv_validator.json` file which would mean that then running
`tendermint init` would never create the `genesis.json` file
which if following the recommended sequence would then fail
since the `genesis.json` was absent.

* cmd/tendermint: Load PrivValidatorFS if existent, lest generate it

Feedback from @melekes

* change logging messages for init cmd

Refs #989

See https://github.com/tendermint/tmlibs/issues/45

Users can now just pass an object that implements the Signer interface.

Prior to this change, a custom Signer would have no knowledge of the private
key stored in the configuration file. This changes introduces a generator
function, which creates a Signer based on the private key. This provides an
opportunity for customer Signers to adjust behaviour based on the key
contents. (E.g. imagine key contents are a key label, rather than the key
itself).

This change allows the default privValidator to use a custom Signer
implementation with no reliance on the default Signer implementation.