updated to zmq 2.5.1 and fixed a few bugs that arose

[dmccarthy-dev]

I updated the zmq lib to version 2.5.1. I also added @_writableState = {needDrain : false}; to the fake socket as its absence was causing an error to be throw.

To fix the bug relating to static content (https://github.com/dan-manges/m2node/issues/8) in fake_socket.coffee I set the @writeBuffer to a copy of the data buffer.

In handler.coffee I found that I had to move the (@pullSocket.connect(options.recv_spec)) code after the onMessage function otherwise messages weren't being processed.

[dan-manges]

Hi Dónal, thanks for this pull request! I haven't had an opportunity to review it yet, but I've added you as a collaborator on GitHub if you'd like to merge it in yourself. I can give you access to the npm package as well if you'd be interested in releasing an updated package. What's your npm username?