add missing Timestamp to Votes

Refs #977

Fixes:

```
panic: Panicked on a Sanity Check: can't encode times below 1970 [recovered]
        panic: Panicked on a Sanity Check: can't encode times below 1970

goroutine 2042 [running]:
testing.tRunner.func1(0xc420e8c0f0)
        /usr/local/go/src/testing/testing.go:711 +0x5d9
panic(0xcd9e20, 0xc420c8c270)
        /usr/local/go/src/runtime/panic.go:491 +0x2a2
github.com/tendermint/tendermint/vendor/github.com/tendermint/tmlibs/common.PanicSanity(0xcd9e20, 0xf8ddd0)
        /go/src/github.com/tendermint/tendermint/vendor/github.com/tendermint/tmlibs/common/errors.go:26 +0x120
github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire.WriteTime(0x0, 0x0, 0x0, 0x1306440, 0xc4201607e0, 0xc420e31658, 0xc420e31680)
        /go/src/github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire/time.go:19 +0x11e
github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire.writeReflectBinary(0xdc9e40, 0xc4201fcf30, 0x199, 0x1317b80, 0xdc9e40, 0xc98451, 0x9, 0x0, 0xdc9e40, 0xc420ead9c0, ...)
        /go/src/github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire/reflect.go:525 +0x22f0
github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire.writeReflectBinary(0xd25400, 0xc42000e2e8, 0x196, 0x1317b80, 0xd92d60, 0xc9a195, 0xa, 0x0, 0xcc8ce0, 0xc420164920, ...)
        /go/src/github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire/reflect.go:530 +0x21e7
github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire.writeReflectBinary(0xcc8ce0, 0xc4209f95b8, 0x197, 0x1317b80, 0xcc8ce0, 0xc9a195, 0xa, 0x0, 0xcc8ce0, 0xc420164920, ...)
        /go/src/github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire/reflect.go:518 +0x2509
github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire.writeReflectBinary(0xd873e0, 0xc4209f9580, 0x16, 0x1317b80, 0xd79400, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
        /go/src/github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire/reflect.go:530 +0x21e7
github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire.WriteBinary(0xd873e0, 0xc4209f9580, 0x1306440, 0xc4201607e0, 0xc420e31658, 0xc420e31680)
        /go/src/github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire/wire.go:80 +0x15f
github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire.BinaryBytes(0xd873e0, 0xc4209f9580, 0x3, 0x8, 0xc420160798)
        /go/src/github.com/tendermint/tendermint/vendor/github.com/tendermint/go-wire/util.go:15 +0xb8
github.com/tendermint/tendermint/blockchain.(*BlockStore).SaveBlock(0xc4201342a0, 0xc420eac180, 0xc420130640, 0xc4209f9580)
        github.com/tendermint/tendermint/blockchain/_test/_obj_test/store.go:192 +0x439
github.com/tendermint/tendermint/blockchain.TestBlockStoreSaveLoadBlock(0xc420e8c0f0)
        /go/src/github.com/tendermint/tendermint/blockchain/store_test.go:128 +0x609
testing.tRunner(0xc420e8c0f0, 0xf20830)
        /usr/local/go/src/testing/testing.go:746 +0x16d
created by testing.(*T).Run
        /usr/local/go/src/testing/testing.go:789 +0x569
exit status 2
FAIL
```

Fixes #934

Handle corrupt WAL file

Send absent validators

blockchain: add tests for BlockStore

Refs #668

Refs #668

add missing Timestamp to Vote

Fixes #974

Add TotalTx to block header

activate PEX reactor by default

Add Timestamp to Proposal/Vote

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

String() and Proposal valid after serializing.
To be safe, but mainly to increase test coverage for the PR

fixes issue with vote serialization breaking the signatures

types/vote_test.go now checks signature on a serialized and
then deserialized vote. Turns out go-wire time encoding doesn't
respect timezones, and the signatures don't check out.

Store it as time.Timestamp locally, encode it as RFC3339 with milliseconds
before signing the canonical form.

fix gometalinter.v2 automatically

Release v0.14.0

it's safe because I added GOPATH to PATH earlier today