fixed with property naming in criteria

This is generally a bad idea to name class properties with the same name as their methods. This for example happens for ```ModelCriteria``` which has a method ```with()``` and a property ```$with```.

This can be troublesome when using for example ```call_user_func_array``` which is used extensively in PHPSpec. For example look at this code: 

```php
call_user_func_array($this->$method, $arguments);
```
so the method ```with()``` does not even get called because an access violation to protected property. I know it can be done like this:

```php
call_user_func_array(array($this, $method), $arguments);
```

But this is what currently PHPSpec does because it is a Mock object that holds mocked methods under property names. I'm not saying this is not a PHPSpec issue as well but nevertheless the property name could be changed to avoid situations like that.