Allow unit testing of routing redirects with assert_redirects.
* ActionDispatch::Routing::RouteSet#recognize_path sets up a Rack::MockRequest with a https scheme when the environment's protocol is 'https://'
* Assert that the given path to assert_recognizes is not a redirect.
* Assert that the generated path in assert_generates is not a redirect.
* Assert a path redirects to an expected url using assert_redirects.
* Assert a path is not a redirect using assert_not_redirects.
* Refacotring of private helper methods in ActionDispatch::Assertions::RoutingAssertions
* Many tests for assert_redirects.
* Allow RouteSet#recognize_path recognize Redirect and all subclasses.