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/meta.proto b/python/protos/meta.proto
new file mode 100644
index 0000000..a308ffa
--- /dev/null
+++ b/python/protos/meta.proto
@@ -0,0 +1,57 @@
+// 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";
+
+message ChildNode {
+    string key = 1;
+}
+
+enum Access {
+
+    // read-write, stored attribute
+    CONFIG = 0;
+
+    // read-only field, stored with the model, covered by its hash
+    READ_ONLY = 1;
+
+    // A read-only attribute that is not stored in the model, not covered
+    // by its hash, its value is filled real-time upon each request.
+    REAL_TIME = 2;
+
+}
+
+extend google.protobuf.FieldOptions {
+
+    // If present, it indicates that this field is stored as external child node
+    // or children nodes in Voltha's internal configuration tree.
+    // If the field is a container field and if the option specifies a key
+    // the child objects will be addressible by that key.
+    ChildNode child_node = 7761772;
+
+    // This annotation can be used to indicate that a field is read-only,
+    // from the perspective of NBI access. Backend plugins and system
+    // internals can update the field but the update requests through the
+    // NBI will ignore for instance a field that is marked as read-only (RO).
+    Access access = 7761773;
+}