Fixed Mouse Button State Issues

Buttons would cancel each others ButtonState.Pressed  out, as well
rotating the mousewheel would cancel all ButtonState.Pressed
Video support for Windows 8 Store apps.
Trying to fix iOS build triggering.
Fixed malformed if test.
Disabled Video.BackgroundColor to make iOS build.
Fixed PlatformResume() for iOS.
Merge pull request #2356 from SickheadGames/iosfix

Fix iOS Build
Added support for bypassing the content pipeline in MGCB
Added missing SurfaceFormats.
Expose PathHelper to MGCB and use its path normalization instead.
Implement web platform (JSIL) stubs and update Protobuild
Fix vsync on WindowsGL

Affects issue #1184
Merge pull request #2358 from thefiddler/gl-vsync

Fix vsync on WindowsGL
Merge pull request #2347 from hach-que/webplatform

Implement web platform (JSIL) stubs and update Protobuild
Renamed all GamePad files to include platform identifiers.
Moved all GamePad code to Input folder.
Added common GamePad class.
Added vibration support to GamePad under XInput.
Fixed web platform to support platform partial methods.
Added copyright header.
Fixed WinPhone platform to support platform partial methods.