Adding support to load Authorizit handler from a PLugin

This is a simple improve that makes possible the define the class that handles the authorization from a Plugin

```php
        'AuthorizitPlugin.Authorizit' => array(
            'class' => array('Users.Lib', 'Authorizit')
        ),
```
What about automatic check access

This feature provides the hability to automatic check if the user can access or not the action, based on a map of settings to action.

So if it's set defaultMap as true, it gonna check what is the action been access and map that as an action of Authorizit, and get the modelClass as the resource to use.
Check if exists the rule for the action and also if the action is not allowed in Auth
Merge pull request #3 from krolow/feature/automatic-check

Automatic Check + Plugin handle