pybind/ceph_argparse: implement 'tell mds'

Signed-off-by: John Spray <john.spray@redhat.com>
vstart: mds * auth caps

...so that the default client.admin identity
can call 'tell mds' things.

Signed-off-by: John Spray <john.spray@redhat.com>
vstart: create fewer pgs for fs pools

Just so that dev clusters come up more
quickly.

Signed-off-by: John Spray <john.spray@redhat.com>
test: unit tests for MDSAuthCaps

Signed-off-by: John Spray <john.spray@redhat.com>
qa: fixup cephtool test when MDS exists

We added MDS resetting code here a while back,
but the order of operations was such that a
"cluster up" was being run between a fail_all_mds
and the point at which we needed the map not to
be interfered with (testing setmap).

Also the new fs create/destroy cycles for testing
EC pool handling were missing calls to stop the
daemons before fs rm.

Signed-off-by: John Spray <john.spray@redhat.com>
qa: cephtool tests for `tell mds.X`

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