Issue description

Currently fetchFromGitHub only allows fetching the source archive.
Some programs (mainly those using autoconf) also provide a release archive that includes a prebuilt configure script.

So a packager has to choose to use either

• fetchFromGitHub and include autoconf / autoreconfHook plus possible some other dependencies
• fetchurl and specify the github url for the release archive.

It would be nice if we extended fetchFromGitHub to provide a way to download the release archive.

The change should be fairly trivial and backward-compatible, I'm just wondering if I'm missing something and this is already possible or if this would be considered an improvement in which case I'll be happy to make the required changes and submit a PR.

nixpkgs $ ag -A5 'fetch(zip|url)' | grep github.\*/release | wc -l
144