settings looks in cwd as fallback
exception 418 added
fixed bricks app creation api

create_app no longer appends dependencies to the main_component,
rather it just adds them to the bricks app.
main component api changed

__call__ must accept both a request and a response
object, optionally resturn a response object otherwise
the initial response is used.

This seemed better than attaching a response to the request object
fixed renderers to accept response objects