Query params sanitized when loading images

[fredrikekelund]

Cool tool! I tried loading a Gravatar image, but noticed that the query params weren't respected by the backend proxy. I had a look at the source and found that proxy.php does indeed strip ?'s.

Wouldn't it be better to parse the incoming URL with some library and then reformat it in order to sanitize it? (I'm no PHP expert, otherwise I could've submitted a PR straight away)