Prepare for inception mounting

 - Let T.application.route.url accept empty defaults and defaults containing /
 - Emit a mismatch event when the main callback does not return a response
 - Add T.application.routeCollection.mount()
 - T.application is a special case of T.application.routeCollection
Add server support

 - Add T.server for the browser
 - Add T.application.listen(), T.application.response.{statusCode, headers}