Replace ReactPHP with Icicle

[andrewvy]

https://github.com/icicleio/icicle

Let's try it out. The current implementation isn't too heavily dependent on ReactPHP. Mostly interested in Icicle's concurrency module.

[lancepioch]

Here's an idea, why not make the core project separate/abstracted enough, that you can use either.

[andrewvy]

Closing this issue because I'm not really wanting to switch frameworks for the time being. :)