allow users to force ipv4 only.

add flag '-4' to commands to force ipv4.
this doesn't work yet because hairtunes unconditionally
uses ipv6 if available.
Handle FreeBSD having openssl in base.
Add ipv4 only support to hairtunes.c.
Pass ipv4_only to hairtunes when -4 is given as an arg.
Add FreeBSD install instructions.
tell FreeBSD people to force ipv4.