[Phaser][DominoMultiplayer] Login page and state machine implemented

Login page is not working yet, just displaying on the screen.

Signed-off-by: Fabio Benigno <benigno.fabio@gmail.com>
[Phaser][DominoMultiplayer] First version of requirements and screen flow

Missing credits, howtoplay and flow overview in the screen flow document.

Signed-off-by: Fabio Benigno <benigno.fabio@gmail.com>