LoginActivity:
  - Sends the username + UUID session id to the lobbyActivity after login
   - Added test login button (for easy testing, a dummy account)
Server Connection:
 - Now receives an UUID from the server when logging in
 - UUID is used to let the server know we are logged in when sending/receiving data from the server.

LobbyActivity:
 - Added player markers
 - Added user login session data
 - Added socket disconnect/reconnect in onStart & onStop
 - Added ConnectToServer AsyncTask
 - Whenever a new location is found it sends it to the server

Added sendLocationUpdate to serverConnection class