Added script to sign release artifacts (apache#592)

src/sign-release.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+#
+
+FILES=$*
+
+for FILE in $FILES
+do
+   echo "Signing $FILE"
+   gpg --armor --output $FILE.asc --detach-sig $FILE
+
+   # Checksum
+   gpg --print-md MD5 $FILE > $FILE.md5
+
+   # SHA-512 signature
+   gpg --print-md SHA512 $FILE > $FILE.sha
+done