Add extended support for friend list

[timiimit]

XMPP server is used to make chat and user persence possible within the game. We need to set-up, configure and connect some XMPP server to our mongodb.

User address for logging in should be <accountID>@prod.ol.epicgames.com/V2:UnrealTournamentDev:::<randomGUID> and password should be access token of currently logged in user.

For initial testing an external XMPP client can be used. One that i know that it can connect to existing EpicGames server is Swift.