For advanced upload assignment, store file count of each submission
into assignment_submissions.numfiles
When counting submissions, if the assignment is open and tracking
drafts, only submissions which has send for marking are counted.
Otherwise, submissions which has numfiles > 0 are counted.
Also change a hardcoded 'submitted' to ASSIGNMENT_STATUS_SUBMITTED.
This patch was originally written by: Sunner Sun <sunner@gmail.com>.
I made some modifation to fixed count_real_submissions() query (ref: MDL-32207) in /mod/assignment/type/upload/assignment.class.php file
- added message provider to manage assignment's messaging
- user_preferences.name length changed form 50 to 255 due to long messaging preference names.