Merged changes from master

Makefile

src/core/channel/client_channel.c

src/core/json/json.h

src/node/binding.gyp

src/objective-c/tests/Podfile

src/ruby/ext/grpc/extconf.rb

src/ruby/ext/grpc/rb_server.c

templates/Makefile.template

tools/run_tests/build_ruby.sh

tools/run_tests/jobset.py