Port to asyncio!

[goodboy]

Now that #44 is in we can begin the move to asyncio based apps! I'm thinking most of the built-ins can be implemented as single coroutine instead of namespace defined callbacks.

autobahn has a good read on the contrast with twisted.

[goodboy]

For py2, I'm thinking we can probably follow pep342 as a guide for implementing our own "inline-callbacks" like in twisted. I think we can probably introspect a callback to see if it's a generator instead of using a different decorator.

For py3.5 we'll obviously use proper coroutines and most likely custom futures for suspending until specific events.