[1.0][filter] Dynamic filters

This attempts to address https://github.com/liip/LiipImagineBundle/issues/268. Other solutions\issues: https://github.com/liip/LiipImagineBundle/pull/42, https://github.com/liip/LiipImagineBundle/pull/271

Use cases:

* Twig:

```twig
{% set runtimeConfig = {"thumbnail": {"size": [50, 50] }} %}
<img src="{{ '/images/dream.jpg' | imagine_filter('thumbnail', runtimeConfig) }}" />
```

* Php:

```php
<?php

$cacheManager->getBroserPath($path, $filter, array(
    'thumbnail' => array(
        'size' => array(50, 50),
    )
));
```

Here you can see filter url:

```
http://liip-imagine-sandbox.dev/appp.php/media/cache/thumbnail_web_path/images/dream.jpg?filters%5Bthumbnail%5D%5Bsize%5D%5B0%5D=50&filters%5Bthumbnail%5D%5Bsize%5D%5B1%5D=50&_hash=PkE1ct4QN1BJct6P6Pqfmb%2FelZ%2F99tFgZjsn29zTs8A%3D
```

and resolved one:

```
http://liip-imagine-sandbox.dev/media/cache/thumbnail_web_path/PkE1ct4Q/images/dream.jpg
```

The url contains `PkE1ct4Q` in path to not mess with pre configured filter caches. It is not possible to remove a single custom cache (at least you the whole path including `PkE1ct4Q`). but remove all has to work quite well.