This installs/starts udiskie, a udisk2 helper, that facilitates
auto-mounting of removable drives.
Note support for umounting is broken in the current Portfolio release,
so disks have to be umounted manually:
udiskie-umount /run/media/<user>/*
I decided to add this to the `depends` and not `pmb_recommends`, because
I felt like 1) this is a feature that folks would expect to work, 2) by
having it in depends, it'll 'fix' existing installs where mounting
removable disks automatically is not implemented
