Added fluent query interface

Still a work in process, but it works as follow

```php
$query = $modelObject->query()
    ->field('name')->equals(99)
    ->addOr()
        ->field('foo')->equals('bar')
        ->End()
    ->addOr()
        ->field('bar')->notEquals('foo');
        ->End();

foreach ($query as $doc) {
}
```