Add script to install protoc-2.6.1

* The latest midonet requires protoc-2.6.1, which must be installed
  from source until a package is provided.

Change-Id: Icbf4b51b5665160801c1a3f3c5a4037d8bb9641b
Signed-off-by: Joe Mills <joe@midokura.com>

scripts/pre_devstack.d/138.get_protobuf.sh

@@ -0,0 +1,28 @@
+#!/bin/bash -xe
+
+# Copyright 2014 Midokura SARL
+#
+# 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.
+
+if [ $MIDONET_GIT_BRANCH == "master" ] ; then
+    wget https://github.com/google/protobuf/releases/download/2.6.1/protobuf-2.6.1.tar.gz
+    tar -xzf protobuf-2.6.1.tar.gz
+    cd protobuf-2.6.1
+    ./configure
+    make
+    sudo make install
+    sudo ldconfig
+    cd -
+    rm -rf protobuf-2.6.1
+    rm protobuf-2.6.1.tar.gz
+fi