Allow simultaneous Shibboleth and local login

This makes several adjustments to the core of OJS to make this happen in
a sensible way:

* Add implicit auth login links (for Shibboleth login) to:

  * User login block
  * Login template
  * User registration template

* Restore change password links and fields on:

  * User home
  * User management page inside journals (for managers)

* Add helper information to password change page about institutional login.
  We can't determine how they logged in at this stage, since implicit
  auth uses the same user source as local login.  This a problem.
Show register links to people logged in but not on journals