upgrade go-etcd client library

third_party/github.com/coreos/go-etcd/etcd/add_child.go

third_party/github.com/coreos/go-etcd/etcd/client.go

...arty/github.com/coreos/go-etcd/etcd/compare_and_delete.go

..._party/github.com/coreos/go-etcd/etcd/compare_and_swap.go

third_party/github.com/coreos/go-etcd/etcd/debug.go

third_party/github.com/coreos/go-etcd/etcd/debug_test.go

third_party/github.com/coreos/go-etcd/etcd/delete.go

third_party/github.com/coreos/go-etcd/etcd/get.go

third_party/github.com/coreos/go-etcd/etcd/get_test.go

third_party/github.com/coreos/go-etcd/etcd/options.go

third_party/github.com/coreos/go-etcd/etcd/requests.go

third_party/github.com/coreos/go-etcd/etcd/response.go

...party/github.com/coreos/go-etcd/etcd/set_update_create.go

.../github.com/coreos/go-etcd/etcd/set_update_create_test.go

third_party/github.com/coreos/go-etcd/etcd/watch.go

third_party/github.com/coreos/go-etcd/etcd/watch_test.go