sandbox: Change how content directory is specified
sandbox: Change how content directory is specified

Firstly, allow specifying multiple --content options, and allow
specifying --content-non-recursive if you really want as well.

Also, don't generate an XDG user directories config. It seems a bit
weird to be doing this and setting each directory to the same location.

outofbits/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker