raftexample: Add test for adding new node to existing cluster
raftexample: Add test for adding new node to existing cluster

mkumatag/etcd,etcd-io/etcd,etcd-io/etcd,ajityagaty/etcd,gyuho/etcd,rnaveiras/etcd,etcd-io/etcd,mqliang/etcd,rnaveiras/etcd,coreos/etcd,mkumatag/etcd,coreos/etcd,ajityagaty/etcd,ajityagaty/etcd,mkumatag/etcd,mqliang/etcd,rnaveiras/etcd,mqliang/etcd,gyuho/etcd