New test to restart entire ONOS cluster before verifying.
New cord tester api to restart entire cluster used by the test.
Changed the restarts to check for onos start using wait_for_onos_start instead of a hard delay.
Added a robot test for restart cluster.

Change-Id: I8dbc163462570a6a8eaf8e7684c790fc3fea8f48
diff --git a/src/test/robot/cluster_controller.robot b/src/test/robot/cluster_controller.robot
index 61269ba..e2a72d7 100644
--- a/src/test/robot/cluster_controller.robot
+++ b/src/test/robot/cluster_controller.robot
@@ -19,6 +19,11 @@
   ${rc}=  Run Cord Tester  cluster:cluster_exchange.test_cluster_single_controller_restarts
   Should Be Equal As Integers  ${rc}  0
 
+Verify Onos Cluster Restart Functionality
+  [Documentation]  Verify ONOS cluster by restarting the entire cluster
+  ${rc}=  Run Cord Tester  cluster:cluster_exchange.test_cluster_restarts
+  Should Be Equal As Integers  ${rc}  0
+
 *** Keywords ***
 Cord Cluster Setup
   [Documentation]  Configure a ${NODES} node ONOS cluster for cord tester