bump to 2.4.0
bump to 2.4.0

lookout/protobuffy,quixoten/protobuf,brianstien/protobuf,ruby-protobuf/protobuf,lookout/protobuffy,film42/protobuf,quixoten/protobuf,film42/protobuf,brianstien/protobuf,ruby-protobuf/protobuf,zanker/protobuf,zanker/protobuf,localshred/protobuf,localshred/protobuf