First pass at a MongoDB databank
First pass at a MongoDB databank

Added a quick class for MongoDB. It's not working in my test suite
yet, but figured I should stash it.

e14n/databank-disk,e14n/databank,e14n/databank-memcached,h4ck3rm1k3/databank,e14n/databank-redis,e14n/databank-mongodb