Merge pull request #1 from shaiker/follower

Follower
added get_followees api
added thumbnail version
commented out recreate thumbnail migration
database yml
uncommented migration
added indices and uniqueness to followships
camelized category name to avoid capital letters diff in names
added get_followers api
image index limit raised to 500
fixed fb friends concorency issue
implemented the feed api with the algorithm
changed new-old images index api to return only 20 images
changed new-old images index api to return all if asked for friends images
when a user signup with facebook, add him as friend to already existing users
fixed sql query of the new images feed
image score - date score is in days (since 1/1/1900) and not in milliseconds
fix similar variable name in image.rb that caused a bug in score calc
add myself to my followers
image age_in_days calculate with decimal point