mon/PaxosService: remove redundant check

_active checks is_active() and rescheduled itself already.

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mon/PaxosService: do not prepare new pending if still proposing

The _active callback can get called while are already proposing.  If
that happens, we should not prepare a fresh new pending but should
wait for the previous proposal to finish.

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mon/Paxos: bootstrap peon too if monmap updates

If we get a monmap update, the leader bootstraps.  Peons should do the
same.

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>