Added test suites for cluster HA data recovery leader follower failover

Added test suites for cluster HA data recovery leader follower failover

    Description: In a 3 node cluster initial inventory shard status is
    verified and following tests are performed.

    - Mininet switch is connected to a follower node and flow is added via
      another follower node. Disconnect the switch and restarts the Leader.
      Connect the switch again once Cluster is formed and verify flow is
      installed in the switch again

    - Disconnect the switch and restarts one of the follower node. Connect
      the switch and verify the flow is installed in the switch again.

    - Disconnect the switch and restarts the Cluster. Connect the switch
      again when Cluster is formed and verify the flow is installed
      successfully.

Change-Id: Ibd01664bc355a41bc95794930b1e40f3468ce858
Signed-off-by: Sanjib Mohapatra <sanjib.mohapatra@ericsson.com>