This change adds a .Request property to the ApiController class that can
be used to access an HttpRequestMessage wrapping the HttpContext.
The HttpRequestMessage is stored in an http feature to make it accessible
to model binders and other infrastructure.
This change adds ApplicationModel conventions that can enable WebAPI
action conventions (verb mapping) and WebAPI overloading.
The conventions activate when a controller has a marker attribute.
ApiController has this attribute, so any ported code will automatically
opt-in.
Also ported some old tests for action selection to our new functional test
framework.
This change includes the basic properties that we're providing for
compatability as well as some functional tests and unit tests that verify
that ApiController can be a controller class.
Ryan Nowak