Fix for issue #610 - Ignore internal and nested types

This change exludes internal and nested types from being treated as
controllers. This is consistent with MVC5's behavior.

DefaultActionSelectionConventions was primarily tested through running
action selection. I wanted to also test the methods with substantial logic
in this class, so I moved a spate of a classes from private classes inside of the
integration tests to public classes so they could be shared. I also added
tests to fill gaps in DefaultActionSelectionConventions, which is the vast
vast majority of this change.
Reacting to System.Security.Cryptograph.Encryption package rename
Move ValueProviders to MvcOptions
Fixes #778
Separating view execution and Razor behavior

* Introducing RazorPage and RazorPageOfT that represent the Razor
  execution aspect of view execution. Moving view execution hierarchy behavior
  (Layout, partial views etc) into a separate RazorView type.

* Renaming IVirtualPathViewFactory to IRazorPageFactory,
  IRazorViewActivator to IRazorPageActivator

* Renaming VirtualPathViewFactor to FileBasedPageFactory to
  correctly reflect what it does.

Fixes #814