Bug fixes and better FreeBSD support

I fixed several bugs.  Chief among them were:
1) Parsing of interface rx/tx statistics on FreeBSD was incorrect
2) "rake test" did not work due to requiring incompatible ruby files in a single process.

I also added a few features, tested on FreeBSD only:
1) Parse interface fib lines
2) Parse ethernet interface media types
3) Parse laggproto and laggport lines of lagg(4) interfaces.