New Badge API

# What's Up
This PR prepares the API for the badges page on Lion. To do this we need to serialize Badges in the same way we currently do Stats.

Also I have changed the way badges are related to user. Previously badge would belong_to the giver. This doesn't seem that useful. Now it belongs to the receiver. This simplifies serialization and points calculations.
What if we had a SQL query matcher for this? I realize it's convenient to reuse the same ruby conditional but it probably doesn't scale that well.