ctdb-recovery-helper: Add banning to parallel recovery

ctdb-recovery-helper: Add banning to parallel recovery

If one or more nodes are misbehaving during recovery, keep track of
failures as ban_credits.  If the node with the highest ban_credits exceeds
5 ban credits, then tell recovery daemon to assign banning credits.

This will ban only a single node at a time in case of recovery failure.

Signed-off-by: Amitay Isaacs <amitay@gmail.com>
Reviewed-by: Martin Schwenke <martin@meltin.net>
Autobuild-User(master): Martin Schwenke <martins@samba.org>
Autobuild-Date(master): Fri Mar 25 06:57:32 CET 2016 on sn-devel-144