Strip google-relate query parameters

Hi.

I have found that varnish with turpentine doesn't send a cached page version if one of Google-related parameters exist. Here is a patch that could solve this and increase hitrate. Taken from http://blog.rac.me.uk/2010/03/03/normalizing_the_url_in_varnish/
However I'm a varnish noob, something could be wrong.

Thanks.