Dockerfile: remove

We don't have build triggers anymore.

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

Dockerfile

@@ -1,5 +0,0 @@
-FROM golang
-ADD . /go/src/github.com/coreos/etcd
-RUN go install github.com/coreos/etcd
-EXPOSE 2379 2380
-ENTRYPOINT ["etcd"]