This will be needed to get better error messages to
users of the D-Bus API. We use glib's builtin gettext
support. No strings marked as translatable yet, we'll
need to mark those user-visible strings carefully and
review them.
With this patch, and the D-Bus activation patches posted earlier the
fprintd daemon is started automatically when needed.
We should have a way to exit it nicely when there are no users
anymore as well...