TASK-6: Initial data communication models and protocol
Merge pull request #8 from nathanmyles/TASK-6

TASK-6: create screen management infrastructure
Merge pull request #9 from DanLatimer/topic/TASK-7

TASK-6: Initial data communication models and protocol
FORMATTING
Merge pull request #10 from nickoram/master

FORMATTING
TASK-6: setup MainMenuScreen

- add label to TextField
- add static list of available games
- open LevelScreen when game is clicked, handing in selected player
- display message to selected user on LevelScreen
- MISC: clear buffer on render()
- MISC: update Viewport on resize()
- MISC: add convenience method in BaseScreen to get Skin