Created Image renderer.

IsOpaque property is not supported yet.
Ability to use a resource image on ImageRenderer.
Changed Android sample to use framework 4.4.
WIP: CarouselPageRenderer.
Allowed handling properties declared in external types.
Removed custom item template from FlipView.xaml
Item template support on CarouselPageRenderer.
Native BooleanToVisibilityConverter.
Update Xamarin.Forms and Microsoft.Experimental.Collection to the latest versions. Fix build errors/obsolete method calls.
Merge pull request #1 from objorke/update_packages

Update the Xamarin.Forms and Microsoft.Experimental.Collection packages