(PUP-3618) Include pkgng provider for FreeBSD

To improve the default state of Puppet on FreeBSD systems, !his work
moves the pkgng provider into core.  Previously, users of the provider
would need to install from the forge module zleslie/pkgng.
It was used for development, but I suppose I'm not clear on what debug output should be omitted since debug is an optional flag that is turned off by default, users won't see this unless they are debgging, in which case it might be useful.