Improve documentation and update broken setup

I recently tried to get this set up for a project I've been working on, but found it incredibly difficult to get set up because of the lack of documentation.

This pull request contains a slightly-more-helpful README, a few minor tweaks to `core.cljs` that were required to get it to compile, and an update to the `bootstrap` script to use newer versions of Clojure/etc.

(Hat tip to @gideonite, who I paired with on this.)