Sync java options in example protos

This makes the protos identical between this repository and the java
repository.

Fixes grpc/grpc-java#1381

examples/protos/helloworld.proto

@@ -29,7 +29,9 @@
 
 syntax = "proto3";
 
-option java_package = "io.grpc.examples";
+option java_multiple_files = true;
+option java_package = "io.grpc.examples.helloworld";
+option java_outer_classname = "HelloWorldProto";
 option objc_class_prefix = "HLW";
 
 package helloworld;

examples/protos/route_guide.proto

@@ -29,7 +29,9 @@
 
 syntax = "proto3";
 
-option java_package = "ex.grpc";
+option java_multiple_files = true;
+option java_package = "io.grpc.examples.routeguide";
+option java_outer_classname = "RouteGuideProto";
 option objc_class_prefix = "RTG";
 
 package routeguide;