Add a simple /__debug__ view, preffed off by default.

[rfk]

To enable the debug page you must secify mozsvc.debug=true in your deployment settings.

The logic for this is copied straight from server-core, with suitable modifications for pyramid.

[tarekziade]

I am wondering if we still need this since Pyramid has the Debug Toolbar that's customizable -- e.g. we could add custom buttons in it

[rfk]

OK, debug toolbar sounds good to me :-)

[tarekziade]

see http://docs.pylonsproject.org/projects/pyramid_debugtoolbar/en/latest/