Add layout base class

The main purpose of this so the the logged_in @reify propery is available in all views, also store self.settings to make the settings more accessible to views, and self.user for the logged in user.

Also, add jquery to repository, because loading it from CDN should not be done in a mission critical web application (dns hijacking possibility)

Also remote $SCRIPT_ROOT variable, it's meaningless, always resolved to an empty string.