202 Geometry conflict checking to background

* wraps check_for_conflicts() in celery based method
* fixes bug on InterventionEditForm where geometry's save() has been called twice

konova/tests/test_geometries.py

@@ -47,6 +47,7 @@ class GeometryTestCase(BaseTestCase):
         Returns:
 
         """
+        self.geom_2.check_for_conflicts()
         conflict = GeometryConflict.objects.all()
         self.assertEqual(1, conflict.count())
         conflict = conflict.first()