Integrated latest demo updates into WP8 demo project

- WP8 demo project now links the original WinGL Game1.cs demo file to
better keep the demos in sync
- Facebook/Twitter button now working in WP8 demo
- Font & FrameworkGUI files now linked to original files in WinGL demo
project
Remove the accidentally added project file in the Gui project
Merge pull request #5 from brainchest/master

Integrated latest demo updates into WP8 demo project