QR scanning for adding friends

[catherinettt]

for A to add B

A ask for B's QR code - Triggers pulling friend list for 5 mins
A scans B and A's device send POST sendRequest to server to create a friend request
B's device fetch list of requests. GET getRequest/user_id
B accepts: POST acceptRequest/friend_request_id
Server creates two new entries in Friends table
A and B are friends! and their friend list should be updated.