fixup client mark_down
msg: allow calling dtor immediately after ctor

Asserting on reaper_stop only made sense if the
messenger had ever been started: as it stood,
one couldn't create and destroy a messenger
without also starting and stopping it.

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>
client: fixup init
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>