feat(go_version): check go version at build time

```
$ ./build
can't load package: package github.com/coreos/etcd:
src/github.com/coreos/etcd/go_version.go:3:1: expected 'package', found
'STRING' "etcd requires go 1.1 or greater to build"
```
Merge pull request #121 from philips/alternative-go-version-check

feat(go_version): check go version at build time
chore(trasnsporter): delete unused variables

just return directly instead of creating intermediate variables
clean up
fix test
cleanup print
use var()
handle readInfo error
clean getMachines
add test package. do not compile test codes with etcd
fix travis
handler version at /version
also return API version
make raft and etcd server
add newJoinCommand func().
make ttl test not so strict. testing server is not fast
use type inheritance
go flavour
wait for exit and release resource
remove unused struct