cache_set breaks display of translated achievements in a multilingual site

In achievements.module, the function achievements_load calls cache_set on line 319. In a multilingual site, this results in pages like /user/%/achievements potentially showing achievements in the wrong language. The site will always display the achievement list in the language of the first user to hit the page and fill the cache.

I think the solution would be to add a language flag to the $cid. I'll tackle this and post a fix...looks like minor changes to a couple of lines of code.