Pull request to add puppet modules to the custom installer

I use composer to install puppet modules when I work with various frameworks to be used with vagrant. Having the ability to have this would be very helpful during development. Please let me know if there is anything else I can do to have this approved.

You can see how this is done by seeing the Gist I made https://gist.github.com/JoshuaEstes/3310a94cb13aef9295e8 that explains using vagrant and puppet with a symfony2 project.