A faster and smaller binary socket.io protocol

This is a squash of 5 commits. Here is a small summary.

The first was the initial rewrite of the encoding, which removes msgpack
and instead uses a sequence of engine.write's for a binary event. The
first write is the packet metadata with placeholders in the json for
any binary data. Then the following events are the raw binary data that
get filled by the placeholders.

The second commit was bug fixes that made the tests pass.

The third commit was removing unnecssary packages from package.json.

Fourth commit was adding nice comments, and 5th commit was merging
upstream.