added a category list template accessible via /categories/
added a category list template accessible via /categories/

azizmb/django-mingus,emorozov/django-mingus,brixtonasias/sk-mingus,brixtonasias/sk-mingus,emorozov/django-mingus,emorozov/django-mingus,azizmb/django-mingus,azizmb/django-mingus,emorozov/django-mingus