Support running without cddb or discid
Support newer ffmpeg, and older sox

sox:
-older versions call 16 bit signed raw s2 (in addition to s16)

ffmpeg:
-newer versions are pickier about the input filename argument location
-use yet another codec name for aac (libvo_aacenc) (ubuntu 12.04)
-some versions like - instead of /dev/stdout /dev/stdin