Hook filters

Created by: myronmarston

This fixes global hook filtering so it can apply based on example metadata in addition to example group metadata.

Do you want some spec coverage for this as well? I meant to add some specs for this as well but ran out of time tonight. Surprisingly, all the changes didn't break any specs...so I guess there wasn't much unit spec coverage of this code in the first place. Let me know if you want any particular specs added for this before you merge it in.