Integrated ServiceStack serialization source code

Integrated a fork of the ServiceStack.Text 3.96 version source code to
Xamarin.Forms.Labs as plugin. Plan is to move generic helper/reflection
files to core & platform DLL’s and make the serializer as lightweight
as possible.

.NET serializer included in the project to be used on the backend if
needed.
Merge branch 'master' of github.com:XForms/Xamarin-Forms-Labs

Conflicts:

samples/Xamarin.Forms.Labs.Sample.iOS/Xamarin.Forms.Labs.Sample.iOS.cspr
oj
	src/Xamarin.Forms.Labs/Xamarin.Forms.Labs.sln