Windows 8.1 UI fixes, roaming saved games

Added an appbar to replace the commands that appear on the bottom right
of the screen. Those inline commands are still visible and will likely
cause a crash when used.
Exporting the game and the light/dark display toggle now work properly.
User's game state is roamed to the cloud and synced between Windows 8
devices. No other changes to the game's functionality or UI have been
made, and it is *still* very touch-unfriendly.