Solve import problem in asset_tags
Solve import problem in asset_tags

Importing moocng.assets.utils before moocng.assets.models produced an import
conflict.

This problem was not detected before as normally moocng.assets.models was
imported before asset_tags, however, it was not possible to run
django_compressor.

GeographicaGS/moocng,GeographicaGS/moocng,OpenMOOC/moocng,GeographicaGS/moocng,GeographicaGS/moocng,OpenMOOC/moocng