Msgpack, integration tests and travis

Hello Brian

Sorry, for the spamming on the other pull-request, I started to push everything because the tests worked locally but not on travis. I should have started an extra branch for that.

I added msgpack with the goal that the request would look exactly the same on pure tornado and zmqweb. That was possible with one minor exception. See 8be41450fb4ecb2cc1019eb3f37e90b576f69c24.

Jean-Louis