WIP: Use materialize-based Django admin

This MR adds django-material-admin (factored out of django-material) so the Django admin also uses materializecss and integrates better.

Open issues:

• Performance issue with frontend script (https://github.com/MaistrenkoAnton/django-material-admin/issues/81)
• Source of materializecss and jQuery (https://github.com/MaistrenkoAnton/django-material-admin/issues/82)