Added Music and Sound Volume on the Options Screen

-Added ChangeOption override to MenuScreen class
-Made the Left and Right keys call the ChangeOption method as opposed to changing the selected option
Added Windows 8 File Access Helper Methods

-The methods can be found in Helper.cs
Merge remote-tracking branch 'origin/Win8FileAccess' into OptionsScreen

Conflicts:
	Top Down Shooter/Top Down Shooter/Helper.cs
Merge branch 'OptionsScreen' into MovementWithCollisions

Conflicts:
	Top Down Shooter/Top Down Shooter/Helper.cs