review: read ISRCs on Linux (LIB-15)

**Please don't merge now**. I can merge this myself, but this is only a couple of hours old so I will review this myself again and would also like feedback from others.

I also couldn't find an "easy" way to gather ISRCs on Linux.
This is a way using SCSI commands directly with the `SG_IO` interface.

MCNs are already added on Linux with 124fcc410df547b0883b42ae2817fce3b72b526b

This is tracked as [LIB-15](http://tickets.musicbrainz.org/browse/LIB-15).