InputFilterPluginManager needs to allow InputInterface retrieval

[demichl68]

Let's say I have various - pre configured - Input classes which are to be built by custom factories..
Now, within my InputFilter class, I want to be able to retrieve these classes via

$this->add(
    [
        'name' => 'foo', 
        'type' => 'myFancyInput'
    ]
);

This fails due to the fact that the InputFilterPluginManager checks the requested service for InputFilterInterface implementation:

https://github.com/zendframework/zf2/blob/master/library/Zend/InputFilter/InputFilterPluginManager.php#L73-L86

IMO the InputFilterPluginManager needs another check for InputInterface, as currently the Input component does not have its own namespace and/or PluginManager