Command::fail(): construct IcingaException printf-like

The first argument of IcingaException::__construct() must be a printf-like format string, but Command::fail() must accept any message string.

library/Icinga/Cli/Command.php

@@ -127,7 +127,7 @@ abstract class Command
 
     public function fail($msg)
     {
-        throw new IcingaException($msg);
+        throw new IcingaException('%s', $msg);
     }
 
     public function getDefaultActionName()