As a new player, I want to be able to create a profile/account with chosen credentials (username and password).

Development Tasks:

[x] On the “home screen” an user can register by clicking on the “register button”.
[x] As an already registered user, a user can log-in into their profile. Upon registering or logging in, one can see the overview page.
[x] Logged-in (only registered users) users can log-out and log back into the registered profile.
[x] There should be an error when a player tries to register with an already chosen username and the password/username fields cannot be empty.