Summary:
        This test is checking the functionality of onos-form-cluster.
        It will first run 7 single node of ONOS and check the number of the node and app.
        Since it is single node, each of them should have 1 node.
        Then, it will form 7 clusters to the ONOS and re-check the number of the nodes, status of nodes,
        and app.
        This time, it should have 7 nodes and installing app from one node should affect the other nodes.
        The status of the Nodes should be "READY"
        Lastly, it will run the Mininet with controllers of 7 nodes to pingall and compare topology
        of ONOS and Mininet.

Required:
        Since it is fixed with 7 nodes, test will be forced to exit unless it has 7 clusters.