Use defrule and defquery vars in ClojureScript

[rbrush]

The current ClojureScript defrule and defquery macros store the rule definition in static state. This is because it wasn't possible to enumerate and inspect vars from ClojureScript when the code was written.

This appears to have changed, as described at the post linked below. So we should consider using real vars in ClojureScript, bringing it closer to its Clojure counterpart.

http://swannodette.github.io/2014/12/17/whats-in-a-var/

[WilliamParker]

I made an attempt at this at https://github.com/WilliamParker/clara-rules/tree/issue140 but the ClojureScript tests fail and I haven't yet figured out why. If anyone else wants to take this up feel free to use this as a starting point. I was expecting this to be some simple cleanup but it isn't turning out that way, and I may not get back to it for a while since it is a fairly low-priority issue for me.