Replace \A and \z regex escapes in anticipation of JS patterns

\A and \z are equivalent to ^ and $ unless in multiline mode, so this is
still correct.
Initial CLJS implementation

Using lein-cljsbuild with simple copy/paste for now. The cljx
preprocessor looks interesting, but makes development more complicated
since cljx files cannot be directly evaluated by the Clojure REPL.
Add example CLJS script

:advanced compilation does not seem to pass arguments to -main…
Update documentation with new location of example.clj
Rename :example -> :prod

Advanced compilation still fails to pass command line arguments…
Add externs file for node process module

process.argv was being optimized away in :advanced compilation mode.
[Frak](https://github.com/noprompt/frak) solves this by adding an
externs file for the node.js process module, so we'll do it to.

Note that that we will not include it in the exported JAR; the onus is
upon the library consumer to handle this sort of thing.
Merge branch 'cljs'

* cljs:
  Add externs file for node process module
  Rename :example -> :prod
  Update documentation with new location of example.clj
  Add example CLJS script
  Initial CLJS implementation
  Replace \A and \z regex escapes in anticipation of JS patterns
Update documentation for ClojureScript addition