initial pass at making puppet-candlepin work for hosted environment

This is the initial round of changes needed to get hosted candlepin standing. There are more changes coming, primarily around additional configurability of candlepin.conf. I am certainly open to suggestions if there are any improvements you might suggest.
I tried doing that at first, and that would indeed be my preference as well, but the only way I could get it to work was with the ugly scope lookup. This is also why I left $db_dialect, $db_driver, and $db_default_port out of the respective postgres and mysql modules (which would have also been my preference). I will give it another go to see if I can figure out how to get the simpler syntax to work. If you have suggestions please let me know.