Adding support for ActivateAttribute via IControllerActivator

This mechanism replaces code in Inject that activated properties
by looking them up by names.


Interesting question, should we inject the above properties as public properties? These both used to be private.

This raises the following questions
1. Should we inject protected and private properties 
2. What about fields
(This kinda follows MEF, so I say yes)

3. Should we get rid of injecting viewengine and service provider, and make the results take care of their dependencies - tracked by https://github.com/aspnet/Mvc/issues/617