add ability to enable/disable turnitin in individual supported modules - also fix some setType errors
Update timedate handling for Moodle 2.4 and consolidate function
add check to prevent timedue from being set earlier than timestart
remove file correctly
If exception occurs make sure we still delete the temp file.
and check response of tiixml correctly
Don't send files that are too large to Turnitin.

Turnitin only processes files up to 20MB and massive files take a long time to upload and can cause a timeout/failure.