Fix issue #5.

Prior to this commit there was a bug where puppet thought that every
installation of puppet was Puppet Enterprise. This fixes the logic so
that it should Do The Right Thing(tm) based on if you have
pe-puppet-enterprise-release installed or not.
Fix issue #7. Confine fact properly.

This should confine the fact to only happening on systems where yum
would make sense (like osfamily being RedHat).