Merge pull request #5 from LouisaBarrett/refactor

Remove old tests for Formatting class
WIP: user refactor
WIP: refactor user
Replace approve_friend with ApproveFriendUseCase
Remove approve method from the Friendship model
WIP remove friendship use case
WIP user refactor
Remove unused methods from Friendship model
WIP: Refactor and implement RemoveFriendshipUseCase
Create Friendship_temp table for changing column names
WIP: change course on table label approach
Remove unused files
Change user_id/friend_id to requester/receiver
WIP: user refactor
Tidy up comments and empty lines
Implement models for requester_pending and receiver_pending friends
Remove user_id and friend_id from friendships
Implement all_friendships and approved_friends models
Fix find_current_friend method for compare view
Consolidate Friendship reject, cancel & remove actions