B+ Revision check & Pins

This was my attempt at creating a PR for issue #8. I was not sure what to do with the hackablePins array as I'm not entirely sure what the purpose of that array is. Hope this helps get things up to date for the B+. Changes seem to be working okay with mine when it comes to reading pins, have no started messing with blinking pins.
Is the B+ still considered REV2 and have the same header? I have a B+ which is why I was making these changes.