Discover not happening after restarting the controller

[pradvara]

• Restarted the controller after shutdown.
• Discovery was not happening and the discovery was failing after serf was installed.

[vvb]

@pradvara this was caused because of missing iptables entries. Resolved by contiv/ansible#247

There is an extra one-time manual step for nodes that were already discovered earlier with older ansible(serf). This is not required for new installations though,

sudo systemctl daemon-reload && sudo systemctl restart serf