Mark abandoned user accounts as such

[ifokkema]

The GV shared LOVD is getting more and more email bounces. Trying to trace the users and trying to reach them at other institutions, takes too much effort.

• Could be combined with an earlier request to have a non-public remarks field for managers and up.
• Mark user accounts as abandoned when we know the email address doesn't work.
  • Update DB, upgrade SQL.
  • Provide interface.
• Handle this mark.
  • Don't ever email this user.
  • Show email address(es) greyed out or unclickable or so, depending on the location.