check for required min version of php every time (frontend and cron), fixes #833

Signed-off-by: Michael Kaufmann <d00p@froxlor.org>

scripts/froxlor_master_cronjob.php

@@ -14,6 +14,12 @@
  * @package    Cron
  *
  */
+
+// validate correct php version
+if (version_compare("7.0.0", PHP_VERSION, ">=")) {
+	die('Froxlor requires at least php-7.0. Please validate that your php-cli version and the cron execution command are correct.');
+}
+
 require dirname(__DIR__) . '/vendor/autoload.php';
 
 \Froxlor\Cron\MasterCron::setArguments($argv);