Use uppercase for the user names to avoid conflicts with Playfab user registration.

[dsrodenas]

• Use uppercase for the user names to avoid conflicts in the Playfab registration of the players. As an example, Playfab considers Dsr and DSR as different user names and allows to register both. But for the display name of those players Dsr and DSR are considered the same name and Playfab throws error by invalid name conflict. This