Update CCHMapClusterController.h

[ghost]

Added updateAnnotations method to header file. In some cases you have to manually update the cluster annotations. I don't know if this is the best solution but in my app works perfectly.

[choefele]

Can you tell me a bit more about when you need to call updateAnnotationsWithCompletionHandler:? I would prefer not to expose this method, because the library should automatically update the clusters when needed.