Merge pull request #569 in ZP/z-push from feature/ZP-1209-autodiscover-apply-a-configurable to develop

* commit 'ae32ce5f':
  ZP-1209 AutoDiscover: updated AUTODISCOVER_LOGIN_TYPE description in config.php and in INSTALL.
  ZP-1209 AutoDiscover: Apply a configurable regex to the login string.