Reactive Slick

Here's the ongoing work on Reactive Slick.

/cc @cvogt for review later
The TCK should be pretty good at this with the way it handles requests (request() single values and do so asynchronously just after being signaled). BTW, I found this article by Doug Lea: http://gee.cs.oswego.edu/dl/jmm/cookbook.html

> Even if a compiler optimizes away a field access (for example because a loaded value is not used), barriers must still be generated as if the access were still present"