* Vulnerability in light client proxy

When calling GetCertifiedCommit the light client proxy would call
Certify and even on error return the Commit as if it had been correctly
certified.

Now it returns the error correctly and returns an empty Commit on error.

* Improve names for clarity

The lite package now contains StaticCertifier, DynamicCertifier and
InqueringCertifier. This also changes the method receivers from one
letter to two letter names, which will make future refactoring easier
and follows the coding standards.

* Fix test failures

* Rename files

* remove dead code

Fixes #1006

```
goroutine 230 [runnable]:
github.com/cosmos/gaia/vendor/golang.org/x/crypto/ripemd160.(*digest).Sum(0xc420ac2af0, 0x0, 0x0, 0x0, 0xc420c01360, 0xc420c01378, 0x20)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/golang.org/x/crypto/ripemd160/ripemd160.go:119 +0x2c9
github.com/cosmos/gaia/vendor/github.com/tendermint/tmlibs/merkle.KVPair.Hash(0x49447e8, 0x7, 0x47ff760, 0xc420048d50, 0xc420aba9a0, 0x14, 0x20)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tmlibs/merkle/simple_tree.go:122 +0x200
github.com/cosmos/gaia/vendor/github.com/tendermint/tmlibs/merkle.(*KVPair).Hash(0xc4200f7ae0, 0xc420aba9a0, 0x14, 0x20)
	<autogenerated>:1 +0x57
github.com/cosmos/gaia/vendor/github.com/tendermint/tmlibs/merkle.SimpleHashFromHashables(0xc420111900, 0x9, 0x10, 0x10, 0xc420ad06c0, 0xc420087500)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tmlibs/merkle/simple_tree.go:87 +0xaa
github.com/cosmos/gaia/vendor/github.com/tendermint/tmlibs/merkle.SimpleHashFromMap(0xc420b987e0, 0xc420b987e0, 0x4941892, 0x3)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tmlibs/merkle/simple_tree.go:96 +0x4d
github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/types.(*Header).Hash(0xc420a541a0, 0x4034f, 0xc420a28530, 0xa)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/types/block.go:177 +0x54a
github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/lite.Commit.ValidateBasic(0xc420a541a0, 0xc420a1e300, 0xc420a28530, 0xa, 0xb, 0x27)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/lite/commit.go:83 +0x1c9
github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/lite/files.(*provider).StoreCommit(0xc4202f2780, 0xc420a541a0, 0xc420a1e300, 0xc420a24870, 0x0, 0x0)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/lite/files/provider.go:71 +0x5e
github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/lite.cacheProvider.StoreCommit(0xc4202f27a0, 0x2, 0x2, 0xc420a541a0, 0xc420a1e300, 0xc420a24870, 0xc420a541a0, 0xc420a1e300)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/lite/provider.go:39 +0x8f
github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/lite.(*cacheProvider).StoreCommit(0xc4202f27c0, 0xc420a541a0, 0xc420a1e300, 0xc420a24870, 0x2, 0xc420a541a0)
	<autogenerated>:1 +0x70
github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/lite.NewInquiring(0xc420990610, 0xa, 0xc420a541a0, 0xc420a1e300, 0xc420a24870, 0x4f3eb80, 0xc4202f27c0, 0x4f3e5c0, 0xc4202f2840, 0xa)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/lite/inquirer.go:29 +0x5c
github.com/cosmos/gaia/vendor/github.com/cosmos/cosmos-sdk/client.GetCertifier(0xc420990610, 0xa, 0x4f3eb80, 0xc4202f27c0, 0x4f3e5c0, 0xc4202f2840, 0xc4200f68a0, 0xc420b21888, 0x470eece)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/cosmos/cosmos-sdk/client/common.go:47 +0x141
github.com/cosmos/gaia/vendor/github.com/cosmos/cosmos-sdk/client/commands.GetCertifier(0x4f46aa0, 0xc4200f68a0, 0xc420b218e0)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/cosmos/cosmos-sdk/client/commands/common.go:82 +0x83
github.com/cosmos/gaia/vendor/github.com/cosmos/cosmos-sdk/client/commands/query.GetWithProof(0xc420a260c0, 0x22, 0x30, 0x0, 0x4947dd6, 0xc42016a000, 0xc420b219a0, 0x4389d85, 0x0, 0x0, ...)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/cosmos/cosmos-sdk/client/commands/query/get.go:73 +0x52
github.com/cosmos/gaia/vendor/github.com/cosmos/cosmos-sdk/client/commands/query.Get(0xc420a260c0, 0x22, 0x30, 0x0, 0x1, 0x0, 0xc420b21a08, 0x43c9c91, 0xc4200a20f0, 0x4947dd6, ...)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/cosmos/cosmos-sdk/client/commands/query/get.go:64 +0x178
github.com/cosmos/gaia/vendor/github.com/cosmos/cosmos-sdk/client/commands/query.GetParsed(0xc420a260c0, 0x22, 0x30, 0x47d1440, 0xc420b984e0, 0x0, 0x1, 0x30, 0x1d, 0x40)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/cosmos/cosmos-sdk/client/commands/query/get.go:31 +0x5f
github.com/cosmos/gaia/vendor/github.com/cosmos/cosmos-sdk/modules/coin/rest.doQueryAccount(0x4f3d300, 0xc4201ee0e0, 0xc420111500)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/cosmos/cosmos-sdk/modules/coin/rest/handlers.go:66 +0x3a5
net/http.HandlerFunc.ServeHTTP(0x4a9d808, 0x4f3d300, 0xc4201ee0e0, 0xc420111500)
	/usr/local/go/src/net/http/server.go:1918 +0x44
github.com/cosmos/gaia/vendor/github.com/gorilla/mux.(*Router).ServeHTTP(0xc4201aab40, 0x4f3d300, 0xc4201ee0e0, 0xc420111500)
	/Users/mappum/go/src/github.com/cosmos/gaia/vendor/github.com/gorilla/mux/mux.go:150 +0xed
net/http.serverHandler.ServeHTTP(0xc4209992b0, 0x4f3d300, 0xc4201ee0e0, 0xc420111300)
	/usr/local/go/src/net/http/server.go:2619 +0xb4
net/http.(*conn).serve(0xc4200b5540, 0x4f3df80, 0xc420086900)
	/usr/local/go/src/net/http/server.go:1801 +0x71d
created by net/http.(*Server).Serve
	/usr/local/go/src/net/http/server.go:2720 +0x288
```

Update state to keep track of this info.
Change function args as needed.
Make NumTx also an int64 for consistency.

uint64 is considered dangerous. the details will follow in a blog post.