Support running Puppet masters from raw gems rather than apt packages.

Ok guys, this is a total work in progress... I'll likely make 30 more commits before its ready, so don't treat this as a merge-able PR. Instead, I'm looking for your feedback on my re-structuring of the classes into parameterized classes. I strongly suggest this model because its far more easily unit testable (see how much simpler the unit tests get). Additionally, it makes things a bit more explicit (rather than doing class-to-class private variable sharing, which is pretty dangerous).
Yep I vote for subclassing the gem install as well.