VOL-1460 Updated core to use voltha-protos instead of local protos
Moved protos to python directory in order to maintain functionaly of containers built there.
Added capability to do local builds of protos
Added instructions on running dep ensure for getting protos.
Updated github.com/golang/protobuf version to v1.3.1

Change-Id: Ia6ef55f07f0d5dcb5b750d7c37b21b71db85bfc4
diff --git a/python/protos/yang_options.proto b/python/protos/yang_options.proto
new file mode 100644
index 0000000..25e6fa7
--- /dev/null
+++ b/python/protos/yang_options.proto
@@ -0,0 +1,74 @@
+// Copyright (c) 2015, Google 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.
+
+// This file contains annotation definitions that can be used to describe
+// a configuration tree.
+
+syntax = "proto3";
+
+option go_package = "github.com/opencord/voltha-protos/go/common";
+
+package voltha;
+
+import "google/protobuf/descriptor.proto";
+
+enum MessageParserOption {
+    // Move any enclosing child enum/message definition to the same level
+    // as the parent (this message) in the yang generated file
+    MOVE_TO_PARENT_LEVEL= 0;
+
+    // Create both a grouping and a container for this message.  The container
+    // name will be the message name.  The grouping name will be the message
+    // name prefixed with "grouping_"
+    CREATE_BOTH_GROUPING_AND_CONTAINER = 1;
+}
+
+message InlineNode {
+    string id = 1;
+    string type = 2;
+}
+
+message RpcReturnDef {
+    // The gRPC methods return message types.  NETCONF expects an actual
+    // attribute as defined in the YANG schema.  The xnl_tag will be used
+    // as the top most tag when translating a gRPC response into an xml
+    // response
+    string xml_tag = 1;
+
+    // When the gRPC response is a list of items, we need to differentiate
+    // between a YANG schema attribute whose name is "items" and when "items"
+    // is used only to indicate a list of items is being returned.  The default
+    // behavior assumes a list is returned when "items" is present in
+    // the response.  This option will therefore be used when the attribute
+    // name in the YANG schema is 'items'
+    string list_items_name = 2;
+}
+
+extend google.protobuf.MessageOptions {
+    // This annotation is used to indicate how a message is parsed when
+    // converting from proto to yang format.
+    MessageParserOption yang_child_rule = 7761774;
+
+    MessageParserOption yang_message_rule = 7761775;
+}
+
+extend google.protobuf.FieldOptions {
+    // If present, the field (a message reference) should be replaced by the
+    // message itself.  For now, this applies only to non-repeated fields.
+    InlineNode yang_inline_node = 7761776;
+}
+
+extend google.protobuf.MethodOptions {
+    RpcReturnDef yang_xml_tag = 7761777;
+}