Set default max_control_nodes if there is none configured.
Set default max_control_nodes if there is none configured.

Change-Id: I5a6590eaaddb3b0a5be223473dd34104c26ce5c4
Closes-Bug:1513993

codilime/contrail-controller,nischalsheth/contrail-controller,eonpatapon/contrail-controller,tcpcloud/contrail-controller,rombie/contrail-controller,sajuptpm/contrail-controller,nischalsheth/contrail-controller,sajuptpm/contrail-controller,sajuptpm/contrail-controller,eonpatapon/contrail-controller,tcpcloud/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,nischalsheth/contrail-controller,rombie/contrail-controller,tcpcloud/contrail-controller,nischalsheth/contrail-controller,nischalsheth/contrail-controller,tcpcloud/contrail-controller,rombie/contrail-controller,sajuptpm/contrail-controller,tcpcloud/contrail-controller,tcpcloud/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,sajuptpm/contrail-controller,eonpatapon/contrail-controller,codilime/contrail-controller,nischalsheth/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,codilime/contrail-controller,nischalsheth/contrail-controller,codilime/contrail-controller,codilime/contrail-controller,rombie/contrail-controller,nischalsheth/contrail-controller,sajuptpm/contrail-controller,codilime/contrail-controller