Report failure to deactivate old master IP in exit code

Report failure to deactivate old master IP in exit code

If we failed to disable the old master IP, the master failover
did not fully succeed, hence that should be reported in the
exit code. Nevertheless, the best is to proceed, as it is
better to have working cluster, albeit only reachable via
the primary IP of the new master node (and not the cluster
master IP), than not have a cluster. Also note, that for
this reason master will start up even if it cannot set
the cluster master IP. So, while there, fix the warning
message as well.

Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>