Fixed #3930 usage of split in letsencrypt cron module.

Till Brehm

2016-05-26 0af38c471a32ede3d267742d7652bcd8b9acbe9d

 server/lib/classes/cron.d/900-letsencrypt.inc.php

@@ -36,7 +36,7 @@
   public function onRunJob() {
      global $app, $conf;

      $letsencrypt = array_shift( split("\n", `which letsencrypt /root/.local/share/letsencrypt/bin/letsencrypt`) );
      $letsencrypt = array_shift( explode("\n", `which letsencrypt /root/.local/share/letsencrypt/bin/letsencrypt`) );
      if(is_executable($letsencrypt)) {
         exec($letsencrypt . ' -n renew');
         $app->services->restartServiceDelayed('httpd', 'reload');