* Combine verification and reverification photo submission end-points.
* Combine verification and reverification Backbone models.
* Allow deletion of verification status in Django admin.
* Initial verification from a checkpoint is associated with the checkpoint.
* Fix critical bug in which an invalid link was sent to Software Secure
for the photo ID image of reverification attempts.
* Ensure that VerificationStatus is append-only and immutable.
* Allow searching by student for verification status.
* Properly pluralize verification status.
* Use ConfigModelAdmin for ICRV config model admin.
