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: I1cc767712bac3694ba4bf9b052765903bce28ae8
Signed-off-by: Sanjib Mohapatra <sanjib.mohapatra@ericsson.com>