Composer support as a gateway to Heroku

Hey Alex!

So, I added composer support to Felix, since that is required to enable Heroku support.

Additionally, I made the settings file default to using environment variables to populate configuration first.  Doesn't change the option for overwriting in a specific install, just makes it pull from the environment by if you don't change anything.

Feel free to reject this, or isolate it on another branch.  I'm still working on converting to mysqli for PHP 5.5 support.