Set module priority to 00.

Ioncube needs to be loaded first (or at least very early). Otherwise you will see an error: `The Loader must appear as the first entry in the php.ini file`. This can be done with `php5enmod` on Ubuntu 14.04 (and possibly other / older php module loading systems) by adding a comment that sets the priority, i.e.,

```
; priority=00
```