Merge pull request #10 from tlock/master

Our improvements
Revert "Fix for sessions with taken attendance show twice in student report."

This reverts commit 5bddb944c0b912ef3f0bc74ff3d99dfae3be1300.
Duplicate fix that will work on MSSQL
Merge pull request #11 from NeillM/fix_MSSQL_issue

Fix mssql issue
Merge pull request #12 from tlock/master

Fixed validation rule for multiple sessions that end date must be after ...
On upgrade, update grade items to 'attendance'