Switches to using protobuf-ruby.

- Adds a dependency to protobuf-ruby in the gemfile
- Updates math.proto to proto3
- Updates math server and client to use protoc protos
- Updates interop server and client to use protoc protos

Also
- Fixes/Updates the noproto samples

TESTED: math_server and math_client can communicate locally.
	Change on 2015/01/07 by temiola <temiola@google.com>
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=83483448