Fixed `columns_for_distinct` of postgresql adapter
Added documentation for the :param option for resourceful routing
skip migration check if adapter doesn't support it
Swallow bundler exceptions when running tests

Let's avoid useless output when testing stuff related to Bundler.
Remove unnecessary include for integration tests.
:scissors:
Fix Baseclass becomes! subclass.
Always construct route objects with Constraint objects
push is_a?(Dispatcher) check in to one place
eliminate dispatcher is_a checks
Constraints#app should never return another Constraints object, so switch to if statement
one fewer is_a check
nothing is passed to `rack_app` anymore, so rm the params
pass a request to `matches?` so we can avoid creating excess requests
pass the request object to the application
Remove duplicated HashWithIndifferentAccess#with_indifferent_access.
push is_a check up to where the Constraints object is allocated
a redirect is not a dispatcher by definition, so eliminate test
we do not need to cache rack_app
stop hardcoding path_parameters and get it from the request