Supports iojs and hopefully later, Node.
Should supports at least Ubuntu, Debian, Linux Mint, Arch Linux,
Gentoo, OpenBSD, FreeBSD, CentOS, OS X and Cygwin.
There's a whole range of fallbacks there, from the regular shasums
to BSD & OS X's more centralised one `shasum` which does everything and
then has fallbacks on 4 of the more popular/new/shiny SSL tools in
PolarSSL, OpenSSL, LibreSSL and BoringSSL.
Dominyk Tiller