Initial websocket support

[jeremyevans]

This adds initial websocket support. It is not complete yet as while
you can create a websocket and send data via the websocket, receiving
data from the websocket does not work, for reasons I've yet to
determine.

This changes the API for route_request, because Reel::Request#connection
is not defined. It includes the request object in a 'reel.request' entry
in the env, so that rack apps can do:

ws = env['reel.request'].websocket if env['reel.request'].websocket?

If anyone could provide a pointer to why receiving data via the websocket
may not be working, that would be helpful.

[tarcieri]

For Rack applications, it might make more sense to use something more Rack-centric, like:

https://github.com/faye/faye-websocket-ruby

[jeremyevans]

I'm building a websocket plugin for the web framework I work on (Roda), and I added support for faye-websocket-ruby first. I'd like to additionally support websockets via Reel/Celluloid, so that people that don't want to use eventmachine have a choice.

[Nowaker]

@jeremyevans Did you have a chance to dig into it? I assumed reel supports websockets natively without having to use Event Machine. That's what Celluloid is for actually...

[jeremyevans]

@Nowaker reel supports websockets, but reel-rack does not. I haven't done more work on this, and don't have plans to do so in the foreseeable future.