mon: add `ceph fs [new|rm|ls]`

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

Conflicts:
	src/mon/MDSMonitor.cc
vstart: update for newfs/rmfs changes

Signed-off-by: John Spray <john.spray@inktank.com>
test/qa: update for MDSMonitor changes

Accomodate changes:
 * data and metadata pools no longer exist by default
 * filesystem-using tests must use `fs new` to create
   the filesystem first.

Signed-off-by: John Spray <john.spray@inktank.com>
mds: journal-related debug messages

Signed-off-by: John Spray <john.spray@redhat.com>
mds: Handle setting 'enabled' in upgrades

Previously was always defaulting to disabled,
should be enabled if MDS map epoch is >1 (i.e.
if an MDS was ever started).

Signed-off-by: John Spray <john.spray@redhat.com>
mon/MDSMonitor: s/enabled/get_enabled()/

Signed-off-by: John Spray <john.spray@redhat.com>
mon/MDSMonitor: fix incorrect comment

Signed-off-by: John Spray <john.spray@redhat.com>
mon/MDSMonitor: log warning while MDS up but no FS

Signed-off-by: John Spray <john.spray@redhat.com>
mds: Update default FS name

From 'default' to 'cephfs' so that it looks
at least vaguely meaningful.

Signed-off-by: John Spray <john.spray@redhat.com>
qa: Update data pool ID for vxattrs test

Signed-off-by: John Spray <john.spray@redhat.com>
mon: Set crash_replay_interval automatically

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