instructors can extend own quiz attempts

closes CNVS-13594

test plan:
  - with and without ember quizzes
    - create a quiz with multiple attempts (not unlimited attempts)
    - as instructor take quiz
    - visit quiz show
    - click link to view history / attempt
      - in right hand area click button to allow an extra attempt
        - action should succeed, ui should update with new number of
          attempts
    - still on history page, choose an earlier attempt
      - in right hand area click button to allow an extra attempt
        - action should succeed, ui should update with new number of
          attempts

Change-Id: I514ff5536e39ab12d2aeba9442085ede221f254c
Reviewed-on: https://gerrit.instructure.com/36430
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Reviewed-by: Derek DeVries <ddevries@instructure.com>
Product-Review: Jason Madsen <jmadsen@instructure.com>