Added friend/unfriend button tests for the user's profile pages
Added partials to show the 'Add friend' and 'unfriend' buttons on the users' profile pages
created user_spec.rb to ensure that the user model responds to 'friends'
Began adding methods for checking if a user is friends with another user
Finished working on adding friends funcionality
Merged Jake Hilborn changes (Friendship model + adding friends) into master