Added comment in `geoapp` tests about PostGIS 2.0 change in ST_NumGeometries.

    def test_num_geom(self):

        "Testing the `num_geom` GeoQuerySet method."

        # Both 'countries' only have two geometries.

        for c in Country.objects.num_geom(): self.assertEqual(2, c.num_geom)

        for c in Country.objects.num_geom():

            self.assertEqual(2, c.num_geom)

        for c in City.objects.filter(point__isnull=False).num_geom():

            # Oracle will return 1 for the number of geometries on non-collections,

            # whereas PostGIS will return None.

            # Oracle and PostGIS 2.0+ will return 1 for the number of

            # geometries on non-collections, whereas PostGIS < 2.0.0

            # will return None.

            if postgis and connection.ops.spatial_version < (2, 0, 0):

                self.assertIsNone(c.num_geom)

            else: