BLTI-195

Switch fully to a single field with the encryption markers.  Teach the services
about encrypted passwords.

TODO: Check to see if the pre-marker code is in production anywhere



git-svn-id: https://source.sakaiproject.org/svn/basiclti/branches/BLTI-195@120421 66ffb92e-73f9-0310-93c1-f5514f145a0a