Revert "This commit was previously reverted in develop:"

This reverts commit da7fe19b91398563359b5703f21e082f9c837e21.
The revert which was previously reverted, has been been reverted back.

LILY-173 convert invitations to new template

The Metronic template is now in use on the invitation page.

To minimize code reuse, a new block {% block form-formsets %} has been added to
form.html.

Conflicts:
	lily/users/forms.py