Version bump to 0.5.1-2
Show warning dialog if session has ended in editor

Closes #3839
- Display a warning modal in the editor routes if the user
  is logged out due to re-authorization problems.  This provides
  a chance to copy any unsaved content before being sent to the
  signin page to log back in.
Delete tokens before deleting a user

fixes #3750

- Updated tests to create tokens for one user. This caused the tests to
  fail for MySQL exposing the bug.
- Delete user's tokens along with posts
Redirect uppercase routes to lowercase version

fixes #3857

- adds uncapitalise middleware which detects uppercase in req.path and
  redirects to the lowercase equivalent
- change the ghost route to a regex, just so it's consistent with other
  routes in the file
Importer: Sanitize UUIDs

Closes #3844
- Before importing, all data is checked for incorrect UUIDs. If check
fails, data is sanitized and outfitted with correct UUIDS.
- Scaffolding allows for easy implementation of additional
sanitization, should that be required in the future.
- Test included, old tests updated.