Improve and extend profile editing tests

Improve and extend profile editing tests

We only ever ran the password changing test here, and not the
half-existing test for changing the bio and homepage.

Fix the tests to actually run both tests. We check that setting bio and
homepage to a valid value works as expected. We also test for invalid
bio (too long) and invalid URLs setting fails. (which is what we want).

- Check that the old /edit/profile/ address redirects to /u/USER/edit/.
- Check that /u/USER/edit/ works as expected
- Check that /u/OTHERUSER/edit/ fails with a 403 Forbidden error when we
  are not logged in as that user. The last remaining test that would be
  useful is to make a user an admin and make sure the admin can edit
  other users' profiles.

Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>