redirect to login on submission show page

fixes CNVS-3982

test plan
- log in as someone who can view a submission
- ensure that you can view the submission
- log out
- navigate to the submission's url
- ensure that you are directed to the login page and that
  no page error occurs

Change-Id: If52a572b0323f1adc5ec3e15338df437d3f28fb4
Reviewed-on: https://gerrit.instructure.com/18048
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Zach Pendleton <zachp@instructure.com>
QA-Review: Marc LeGendre <marc@instructure.com>
do not allow GB1 when course enrollments are > 250

closes #CNVS-4173

test plan:
- in rails console run:
  Setting.set('gb1_max', '0')
- start your rails server
- go to the gradebook for any course
- it should redirect to courses/*/gradebook2
  and the button to go back to gb1 should not be present

Change-Id: I5e08490f173898927f80496239d176ca0c92168b
Reviewed-on: https://gerrit.instructure.com/18068
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cameron Matheson <cameron@instructure.com>
QA-Review: Cam Theriault <cam@instructure.com>
add undelete option to course batch update api

fixes CNVS-4056

test plan:
 - delete some courses via the UI or API
 - use the course batch update API with event=undelete to bring
   them back

note: while you can undelete a course via its sis id, this only
works if the course was _deleted_ via sis.  if you delete a course
via the UI or API, its sis ID is cleared.  this is by design:
https://gerrit.instructure.com/#/c/3520/

Change-Id: I402dd1e0bdfc6ae639e1781f16ae5e629ca9f87a
Reviewed-on: https://gerrit.instructure.com/18062
Reviewed-by: Mark Severson <markse@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Adam Phillipps <adam@instructure.com>
update boot.rb for the newest brightbox 1.9 packages and ruby 2.0

This doesn't add full ruby 2.0 compatibility, just fixes one bootup
issue. Brightbox backported a similar gem/require change to their latest
1.9 package, this fixes the same error with that package as well.

Change-Id: If2905f1f9fa0eb145efa1caefcf005b5f991f785
Reviewed-on: https://gerrit.instructure.com/18085
Reviewed-by: Stanley Stuart <stanley@instructure.com>
QA-Review: Stanley Stuart <stanley@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
use mysql2 gem for mysql

closes CNVS-4199

Change-Id: I81a14efca365a61ff9e5d29892ec95ace64aabb3