issue allenhwkim#331, changed 'marker' to 'customMarker' in event

Author: allenhwkim

directives/custom-marker.js

@@ -151,7 +151,7 @@
 
         element.bind('$destroy', function() {
           //Is it required to remove event listeners when DOM is removed?
-          mapController.deleteObject('customMarkers', marker);
+          mapController.deleteObject('customMarkers', customMarker);
         });
 
       } //link