Guide.ShowKeyboardInput for WinRT

I've implemented the Guide.ShowKeyboardInput for WinRT. It uses a XAML
to draw a PopUp with an InputBox (or PasswordBox) and two buttons, one
for OK and other for Cancel. It is similar to the MessageDialog.
Merge branch 'develop' of https://github.com/mono/MonoGame into winrtGuideShowKeyboardInput
Now compiling again on WP8 branch.
BeginShowKeyboardInput fixed for iOS
Added support to load from parent directory using ".." in ContentManager
Support for multiple parent dirs after eachother
Remote status bar hiding from this tag as it needs to be discussed
Use URI to resolve the path
Merge branch 'develop' of https://github.com/mono/MonoGame into winrtGuideShowKeyboardInput

Conflicts:
	MonoGame.Framework/MonoGame.Framework.Windows8.csproj
	MonoGame.Framework/Windows/GamerServices/Guide.cs

Merged with new Protobuild process.
Merge branch 'develop' of https://github.com/mono/MonoGame into develop
Merge branch 'develop' of https://github.com/mono/MonoGame into winrtGuideShowKeyboardInput
Merge branch 'develop' of https://github.com/mono/MonoGame into ioskeyboardfix

Conflicts:
	MonoGame.Framework/MonoGame.Framework.iOS.csproj
Remove iOS csproj in favor of Protobuild
Updated Protobuild definition
Split Video and VideoPlayer files on a per-API basis.
Removed Video from Normalize, as the route of loading raw files through the ContentManager will soon be killed off.
Merge branch 'MediaPlayerSplit' into VideoPlayerSplit
Merge.
Merge branch 'develop' of https://github.com/mono/MonoGame into develop
Merge branch 'develop' of https://github.com/mono/MonoGame into develop
Merge branch 'develop' of https://github.com/mono/MonoGame into develop