This commit will add the index for the question_reference
and the question_set_reference table if its not already
added. This commit will also implement the logic of adding
the question area and component in the joins of the question
reference table in order to make sure any other plugin using
the qbank api does not conflict with each other.
The versioning changes will require some major changes
in the backup and restore of question bank and its
elements. This change introduces those changes to make
it compatible with the new world of versioning in question
bank. This commit also removes quiz_slots fields and
quiz_slot_tags table.
This commit will also introduce the versioning db
structure and some major changes to the quiz
and quiz attempts for the question, random
question and the view.
This commit implements the behat changes for versioning
in core question and associated locations.
