Improve TenantPrivilege
diff --git a/xos/core/models/service.py b/xos/core/models/service.py
index f53f2e7..83fd3e8 100644
--- a/xos/core/models/service.py
+++ b/xos/core/models/service.py
@@ -824,6 +824,7 @@
     def __unicode__(self):  return u'%s' % (self.role)
 
 class TenantPrivilege(PlCoreBase):
+    id = models.AutoField(primary_key=True)
     user = models.ForeignKey('User', related_name="tenantprivileges")
     tenant = models.ForeignKey('Tenant', related_name="tenantprivileges")
     role = models.ForeignKey('TenantRole', related_name="tenantprivileges")