MP1 Integration

Naka-console type ang GUI na lumalabas. Tapus bale matchmaking system
ang iimplement natin. One server handles many clients. A client can
initiate an invite to another client once he/she knows the other
client's username. Once the other client accepts the invite, they will
proceed to the game proper.

I'm currently looking in the BiMap class in guava-14.0 library to search
through pairs of clients efficiently (a client must be unique in that
bi-directional map). The server will take action based on two things:
whether the client has a pair in the map and the messages the client has
sent to the server.