Add some controllers + tests

* Replace remove fingerprint-check with proper signature verification
* minor refactor to improve readability

Replace JQuery with native javascript

Feature: generic templating / emailing

Make getContents public to be able to use Twig templates for other things then web pages (i.e. mail templates)

This reverts commit 2fc62f71.

Add missing quote in example code for customauth

This reverts commit 0d433ac5.