makepasswd: builds and installs.

Uses work-arounds to build directly from upstream source on OSX.  makepasswd
has a default character set and password length. Formula test validates that
the binary produces a passwd within these defaults. No manpage yet!
makepasswd: 'man makepasswd' page builds & installs

Upstream project doc Makefile is a bit *nix-specific, so this formula works
around it by just using docbook2man.  However, introduces a formula dep to
docbook2x (which in turn requires a CPAN module install).