Add helper view for ACL

I have few advices here:

> Wojciech Nowogrodzki said: In view you have identity() helper - so you have logged user data. I.e. if your identity data is an object with permissions - you have it. But if not - if I were you - I would write own helper to check permissions in view.

And http://framework.zend.com/manual/current/en/modules/zend.view.helpers.advanced-usage.html#writing-custom-helpers
