Avoid code churn

Author: NoahStapp

django_mongodb_backend/gis/operations.py

@@ -131,8 +131,8 @@ def gis_operators(self):
         "BoundingCircle",
         "Centroid",
         "ClosestPoint",
-        "Distance",
         "Difference",
+        "Distance",
         "Envelope",
         "ForcePolygonCW",
         "FromWKB",