task/mds_journal_migration: fix cleanup

Previously this was remounting in the background
which meant that if a workunit was executed immediately
afterwards it could put files in the mount dir before
the FS was mounted, causing the mount to fail.

Signed-off-by: John Spray <john.spray@redhat.com>
Fix package_version_for_hash() call

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
task/ceph_fuse: enable umounting from config

This is for any test config that needs to run
some workunit with clients unmounted.  It allows
you to go toggle the mountedness of a client as
you go up and down the stack list this:

- ceph-fuse:
    client.0:
        mounted: true
- workunit:
    clients:
        client.0:
        - fs/misc/trivial_sync.sh
- ceph-fuse:
    client.0:
        mounted:
            false

The initial use case for this is running the
cephfs_journal_tool_smoke.sh workunit, which
tests administrative operations that are meant
to be run on an unmounted filesystem.

Signed-off-by: John Spray <john.spray@redhat.com>
task/ceph: add ceph.stop task

So that we can explicitly stop daemons on demand.  Useful
for MDS tool tests that want the MDS daemons not to be running,
is this is more solid and explicit than doing e.g. "ceph mds stop"
from within workunits.

Signed-off-by: John Spray <john.spray@redhat.com>