docker: Use proper release tags with docker. (#2680)

Fixes #2677

buildscripts/docker-flags.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+#
+# Minio Cloud Storage, (C) 2016 Minio, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+minio="github.com/minio/minio"
+version="2016-09-11T17:42:18Z"
+release="RELEASE.2016-09-11T17-42-18Z"
+commit="85e2d886bcb005d49f3876d6849a2b5a55e03cd3"
+
+echo "-X ${minio}/cmd.Version=${version} -X ${minio}/cmd.ReleaseTag=${release} -X ${minio}/cmd.CommitID=${commit}"
+