iOS: modify the method of start scheduling notifications for a newly joined experiment
iOS: stops timer and location update in PacoLocation's dealloc method
iOS: send the initialization of PacoLocation to main thread to fix the location error message.
iOS: modified log information
iOS: rename methods
iOS: code refactoring and bug fixing.
iOS: remove notifications for stopped experiment
iOS: if a time out notification was responded by user, consume it silently.