Add simple ViewModel based NavigationService
Updated Forms nuget and renderers for IOS and Android
Merge branch 'viewmodel-navigation'
Updating samples
Include mvvm sample
Updated WP sample
Added serializer plugins

In the main package XML and JSON serializers using the runtime
serializers. As plugins the 3rd parties:

Json.NET (portable)
ServiceStack V3 (NET45, iOS, Android & WP8 versions) - only JSON
serializers for now
ProtoBuf.Net (portable)
Merge branch 'master' of https://github.com/XForms/XForms-Toolkit

Conflicts:
	src/XForms.Toolkit/XForms.Toolkit.WP/XForms.Toolkit.WP.csproj
Fix mvvm navigation sample
Update README.md
Update README.md
Update README.md
Screenshots for iOS and Android
Added XML documentation to device classes
Updated read me for phone service
Merge pull request #3 from XForms/master

Merge from main