Begin importing FreeBSD interface management

This work converts the implementation for FreeBSD network interface
management in the puppet-freebsd module into ruby and imported into this
module.

Now the bsd::network::interface has a mostly consistent interface
between freebsd and openbsd.  There are small items that may need
adjusting, so still not ready for primetime until the api interface
solidifies, but its getting there.
Merge pull request #20 from xaque208/freebsd

Begin importing FreeBSD interface management