Feature CollectionInputFilter

Currently, there is no way to directly specify a *single* InputFilter that can loop and filter a subset of data (for example when using the Collection Element on a form). This makes it near impossible to inject dependencies into custom validators used on collections, etc.

This PR introduces a CollectionInputFilter which allows attaching a single input filter to a collection of data in the following way;

```php
$this->add(array(
    'type' => 'Zend\InputFilter\CollectionInputFilter',
    'inputfilter' => new InvoiceItemFilter()
), 'items');
```
 or

```php
$items = new CollectionInputFilter();
$items->setInputFilter(new InvoiceItemFilter());
$this->add($items, 'items');
```