Add a basic unit test

[peterschwarz]

I found setting up the unit tests on node a bit painful, given that there's pretty limited documentation on running them in a node context, as well as the addition of the :hashbang compiler option. This addition would certainly save people the trouble of getting these settings right.

[swannodette]

@peterschwarz not interested in integration with clojurescript.test until it supports :none optimizations.

[mike-thompson-day8]

That's a solved problem:
https://github.com/mike-thompson-day8/cljsbuild-none-test-seed

[swannodette]

@mike-thompson-day8 I'll consider it solved when @cemerick integrates this type of thing into clojurescript.test itself