Fix the share process --> use the notification framework for UPtasks
Improve the notification process (stability)
- error when UPTask is null
Implement the UserProfileTask for file deletion
Minor comment improvement
Move method to super-class to reuse it later
Implement the UserProfileTask for adding a file
Activated notification for addfile
Download is a chain instead of a tree now (can be improved later)
Handle user task queue when login
Implement the move file user profile task