This patch adds lots of webservices to the assignment module.
* mod_assign_revert_submissions_to_draft
* mod_assign_lock_submissions
* mod_assign_unlock_submissions
* mod_assign_save_submission
* mod_assign_submit_for_grading
* mod_assign_save_grade
* mod_assign_save_user_extensions
* mod_assign_reveal_identities
* mod_assign_copy_previous_attempt
All features such as reopening attempts and marking workflow are supported through
the save_grade and save_submission functions.
Uploading files is supported by sending draft item ids for the files_filemanager param the same functions.
This change makes the attempt history display for teachers and students
even when there is no grade (e.g. blind marking). It also will show the previous
attempt in the grading table when a submission has been newly reopened (instead
of a blank submission).
