Create gem with bins

This is the first pass of the gem which contains code that _should_ make it easy to get access to the right binaries and falls back to the data folder if it doesn't exist.

I'm totally new to this stuff, so I've no doubt done something stupid. Please critique thoroughly.

First push of the gem is up here: https://rubygems.org/gems/meterpreter_binaries

MSF PR incoming too.