GFS2: Add some more info to uevents

With each uevent, we now always include the journal ID. We
can't call it JID since that is already in use by some of
the individual events relating to recovery, so we use
JOURNALID instead. We don't send the JOURNALID for spectator
mounts, since there isn't one.

Also the ADD event now has both RDONLY and SPECTATOR information
to match that of the ONLINE event.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>