Updates to make DYE work with Django-CMS 3.

Created by: qris

Note that:

• some CMS plugins have changed names, so we need some conditional code in cookiecutter if we want to support Django-CMS 2 going forward.
• not all plugins tested yet.
• cms_redirects may be superceded by built-in functionality now.
• going back to official releases of ckeditor may undo bug fixes in our fork.