Merge pull request #1589 from nicolasnoble/ruby-cleanup

src/ruby/ext/grpc/extconf.rb

src/ruby/ext/grpc/rb_byte_buffer.c

src/ruby/ext/grpc/rb_byte_buffer.h

src/ruby/ext/grpc/rb_call.c

src/ruby/ext/grpc/rb_call.h

src/ruby/ext/grpc/rb_channel.c

src/ruby/ext/grpc/rb_channel.h

src/ruby/ext/grpc/rb_channel_args.c

src/ruby/ext/grpc/rb_channel_args.h

src/ruby/ext/grpc/rb_completion_queue.h

src/ruby/ext/grpc/rb_credentials.c

src/ruby/ext/grpc/rb_credentials.h

src/ruby/ext/grpc/rb_grpc.h

src/ruby/ext/grpc/rb_server.c

src/ruby/ext/grpc/rb_server.h

src/ruby/ext/grpc/rb_server_credentials.c

src/ruby/ext/grpc/rb_server_credentials.h

tools/run_tests/build_ruby.sh

tools/run_tests/run_tests.py