Fix invalid urls generated by _url

Someone let us know that your flairsync script had recently stopped working. There was an excess slash in `_url`  here that caused it to generate urls like `http://www.reddit.com/r/deimorz//api/flairlist`. Apparently Akamai was handling this and stripping out the extra slash, but now that we've switched away this is no longer happening, and the script is generating 404s.