Update to accommodate some changes in the Humble Bundle pages

Files are now served over https on a different CDN. This means snarf
no longer works; use curl instead. This eliminates a dependency but I
find the way you specify arguments to curl a little clunky.

Also, the Brütal Legend filename was screwing things up -- seems that
beautifulsoup was getting confused about the encoding of the
file. Force utf-8. This seems to speed parsing up by quite a
bit. (Wish I'd known that earlier..)
Towards supporting comedy/audio

This at least supports unpacking the zip files that they use to pack
comedy videos in, but there are some logistical questions about
albums, and unpacked videos aren't recognized (so humbug wants to
download them again).