Support websocket compression

[casprack]

In index.js, perMessageDeflate is set to false (here). There's a accompanying comment indicating that this was because of a bug in websockets (here). This bug has been fixed and it would be great if compression was supported in this package, potentially even by default.

I did some testing in my environment and everything seems to work perfectly when compression is enabled, and delivers significant reductions in network traffic.

[mikemintz]

Good find! Would you mind submitting a PR enabling compression by default, and I can go ahead and bump a new version.

[shareefalis]

Created a pull request. Can you go ahead and merge it?