modularize system dependency setup

This includes support for OS X and apt based systems (Ubuntu/Debian) only in this pull request. These two files should be informative enough to get other *nix based systems included.

I'd suggest this approach be limited to package management based systems only. If users can't get up and running from executing `script/bootstrap` then they should be handling their dependency issues themselves. Package management tools like apt, brew, yum, portage, etc, are my thinking here. A wiki page to direct folks to which packages are needed in order to get the app functional would probably be my best directive on non-PM systems.

This is just my thinking of a way to implement support for multiple systems during the bootstrap process. I don't even think that the method of finding out which PM to use is the most logical choice but it is what I had on hand at the time.

Now for pretty pictures:
- Ubuntu 12.04 ![apt](https://f.cloud.github.com/assets/423711/42668/a47725f6-5642-11e2-8299-c69e8ad40e09.png)

- Mac OS X 10.7 ![brew](https://f.cloud.github.com/assets/423711/42681/04ca5a20-5645-11e2-90b1-bf3c3173ea58.png)

Both of these install processes required extra packages to be installed in order to succeed. OS X needed media-info and Ubuntu needed mysql-client.