THE BLACKLIST

Per https://github.com/benbalter/gman/pull/24#issuecomment-30012518, cc @jlord.

This adds support for a edu blacklist of non-edu imposter domains that don't necessarily pass the educational sniff test, but otherwise end in a whitelisted TLD. `si.edu` is the start, but there should be more out there.

A few friction points I hit in building the PR, glad to break out if you'd like things to be cleaner:

* Added `*.gem` to `.gitignore`
* moved `.rbenv-version` to `.ruby-version`
* bumped to ruby 2.0.0