support version and basic stats
version name etcd 0.1
gofmt
add RawGet that will return Response struct
in this case, err should be nil. avoid dereference
simplify machine list. do not need a separate struct to store machines, since we have already stored them into etcd store.
add space in comments
change version from 0.1 to pre-0.1
allow pervious machine to rejoin to the cluster without pervious log
fix wrong error
Merge pull request #47 from xiangli-cmu/master

support version and basic stats