Implement UI design for the game page

https://invis.io/NG3VJKWYF
Graphic assets are in the Invision folders

Missing elements:

• how to scroll history of moves
• user information in the Players tab
• top left menu: content not defined yet (but the current one is fine for the time being)
• "I'm done" button: not designed (but should be there anyway, will take care of it later from a design standpoint)
• bottom bar content is not well defined yet, so no focus on it

NB: the game experience would benefit from animations. I'll have a github issue just for that.