'Never' question status is redundant

It seems to me that the 'Never' question status is not needed, or at least there is no point in storing a question status of 2 in the database... If a question is set to 'Never' be shown on a quiz, it is the same thing as there being no record of it in quiz_questions. Making this change will reduce the amount of data required to be stored for quizzes and also seems like it will also simplify the process of retrieving quiz questions.

Will need to:
- Set questions' default status to 'Never' instead of 'Random'
- Update the update_quiz_question function to delete a record from quiz_questions if its status is set to 2.