Added 'instances:clone_instances' permission

Replaces 'can_clone_instances' user attribute

instances/models.py

@@ -1,4 +1,7 @@
-from django.db.models import Model, ForeignKey, CharField, BooleanField, DateField, CASCADE
+from django.db.models import (CASCADE, BooleanField, CharField, DateField,
+                              ForeignKey, Model)
+from django.utils.translation import ugettext_lazy as _
+
 from computes.models import Compute
 
 
@@ -11,3 +14,15 @@ class Instance(Model):
 
     def __unicode__(self):
         return self.name
+
+class PermissionSet(Model):
+    """
+    Dummy model for holding set of permissions we need to be automatically added by Django
+    """
+    class Meta:
+        default_permissions = ()
+        permissions = (
+            ('clone_instances', _('Can clone instances')),
+        )
+
+        managed = False