File: purge thumnbails using a proper domain

We used to send purge requests to images.wikia.com domain with URLs without cb / timestamp part.

This changeset uses a proper domain (with ``nocookie.wikia.net``) and adds a timestamp to the URL

```
Purging URL http://images.macbre.wikia-dev.com/__cb20111213221641/poznan/pl/images/0/06/Gzik.jpg via Scribe
Purging URL http://images.macbre.wikia-dev.com/__cb20111213221641/poznan/pl/images/thumb/0/06/Gzik.jpg via Scribe
(...)
```

@prein / @ljagiello / @Wikia/platform-team