Script to build OS X native app bundles, expanded OS X docs

Included a hack-y but working script to build self-contained OS X app bundles out of the scripts that take care of Python module dependencies.

Also expanded the docs to talk more about OS X - how to get the scripts running there, and also how to build app bundles.

If you want to host a (75M!) .dmg image with the app bundles on your website where you keep the Windows .exe, let me know and I can provide it.