http://blog.ralch.com/tutorial/golang-working-with-tar-and-gzip/.

CopyFile copies a file from src to dst.

http://stackoverflow.com/questions/32482673/golang-how-to-get-directory-total-size.

ParseSize parses disk size string (e.g.

TODO: change this to api; like in here: https://www.versioneye.com/python/losetup/2.0.7 or here https://github.com/karelzak/util-linux/blob/master/sys-utils/losetup.c.