A user can join a lobby many times

[Sawarni Swaroop]

We have to check the lobby array if the user is already in a lobby.

Steps to create this bug.

• Create a lobby with any name (say Mayur).
  

• Create a room with the same username.
  

• Connect with a new user (say Harshit).

• Join the lobby with room_id as Mayur.

• Join the lobby again with the same username Harshit and room_id Mayur.
  

[Justin Mathew]

Fixed