Use canonical version of hello_world.proto (#135)

Closes #134

Author: chalin

examples/src/main/proto/hello_world.proto

@@ -1,4 +1,4 @@
-// Copyright 2015 gRPC authors.
+// Copyright 2015 The gRPC Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -11,17 +11,19 @@
 // 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.
-
 syntax = "proto3";
 
-package io.grpc.examples.helloworld;
-
 option java_multiple_files = true;
+option java_package = "io.grpc.examples.helloworld";
+option java_outer_classname = "HelloWorldProto";
+option objc_class_prefix = "HLW";
+
+package helloworld;
 
 // The greeting service definition.
 service Greeter {
   // Sends a greeting
-  rpc SayHello (HelloRequest) returns (HelloReply);
+  rpc SayHello (HelloRequest) returns (HelloReply) {}
 }
 
 // The request message containing the user's name.