Change the behavior of Connection#end. It now calls the given callback immediately if the request body is already recieved.

This fixes a bug where the incomming request hangs when Connect middleware is used to parse the request body.
Fix the mode naming to match conventions in ViewBuilder
Fix some this scoping issues
Relieve apps from attaching some usually useful Connect middleware.

Note apps will still need to attach session and CSRF handling themselves, if they need it.