Access right mixin

Closes #588 (closed)

arkindex/dataimport/models.py

@@ -303,10 +303,6 @@ class Repository(models.Model):
     git_ref_revisions = models.ManyToManyField('dataimport.Revision', through='dataimport.GitRef')
     memberships = GenericRelation('users.Right', 'content_id')
 
-    ADMIN_LEVEL = 100
-    EXECUTE_LEVEL = 50
-    READ_LEVEL = 10
-
     class Meta:
         verbose_name_plural = 'repositories'