message: Add (optional) shape and type fields to fetch.
diff: @@ -38,6 +38,10 @@ message Feed {
  message Fetch {
  TensorId id = 1;
  string name = 2; // Optional name for generated code.
  +
  + // Optional shape and data type. If specified, may be used for validation.
  + TensorShapeProto shape = 3;
  + DataType type = 4;
  }
  // Variable represents a resource variable with the given name, shape and type.
  