Use https due to new 302 redirects

Google are now issuing 302 redirects from `http://translate.google.com/` to `https://translate.google.com/`. Trouble is, the being passed in is lost in the redirect, so the plugin has stopped working (for me at least). It works if I change the target url to `https://` instead.

PS> Thanks for a handy plugin, real time saver for expats :+1: