US-1: Generate shareable URLs

[gtoutin]

Users need a way to ask people to become their friends. This ticket provides for the generation of a URL to send via an external communication service that will allow a non-friend user to send a friend request. This is important because this is how people join the network. Depends on finding a way to sync posts across computers

This is done when

• There is a button to generate an invite URL for a user on their author page
• Page is created where user can send friend request

Acceptance criteria

• As another user, following that URL will allow them to send a friend request from their account
• A non-local user can use the link

Test cases

• A URL is generated
• A non-local user can follow the URL to the friend request page
• A non-local user can successfully send a friend request

[gtoutin]

• Change signaling server code to p2p connect two users without them being friends

The link will be signalingserveraddress/invite/somekey where somekey is a randomly generated key. It should expire after a certain amount of time. The server knows this key refers to an invite by user A. If user B calls it with that key, it will make p2p connection between A and B even though they are not friends.
(This technique can be used in the future to do things without 2 users being friends).

Look out: do changes need to be made to other parts of the program given they are not friends yet? This invite link should only be used to establish a friendship.