Added singleton injection into framework.  Push singleton objects via static method:

Framework.InjectAsSingleton<T>(T dep)
ex:
Framework.InjectAsSingleton(new Foo());

Resolve your object via:
Framework.ResolveSingleton<T>()
ex:
var foo = Framework.ResolveSingleton<Foo>() as Foo;

Removed doxygen documentation from this repo, will make a clean repo for it at unity-framework-doc