Merge branch 'adexpirywarn'

* adexpirywarn:
  make sure AD pass expiry message is never shown twice
  do not hardcode profile link in AD pass expire message
  translatable AD expiry warning and link to update profile page
  Don't return any data for non-existant users
  do not query AD for empty user name
  always check expire time when configured
  Check password expiry times in Active Directory backend