Merge pull request #426 in ZP/z-push from bugfix/ZP-916-koe-even-after-setting-zarafahidden to develop

* commit 'ef361bd8':
  ZP-916 Undo removal of SYSTEM check.
  ZP-916 Only define constants if they are not defined yet.
  ZP-916 Log message when account is hidden.
  ZP-916 Remove space in PR_EC_AB_HIDDEN constant name, check if value isset().
  ZP-916 Query and check for PR_EC_AB_HIDDEN.