using bundle.list for bundle files

This is https://github.com/racker/virgo/pull/442 squashed.

Related change in `virgo-base`: https://github.com/racker/virgo-base/pull/23

Tested on:
* centos63-x86_64
* centos58-x86_64
* ubuntu1204-x86_64
* ubuntu1304-x86_64
* win2012_x64
* Mac OS X 10.8.4 x86_64 (case-insensitive FS)