GIF caching
    Most of the time `cptc` consumes by downloading avatar and generating gifs.
    It could be fixed by using some reverse proxy that has caching enabled, but
    there's a smarter way to do caching.

    Instead of watching for time of avatar downloading, `cptc` should look at
    the avatar hash which is got on the first request to the discord (about
    getting info about the user). If avatar hash has changed - it means that
    user changed it, and so `cptc` should redownload avatar and regenerate gif.
    If there's already a generated gif, `cptc` should return that one.