CBQE-0: Failure scenarios for graceful failover:kill node, stop node

These tests would test out re-try logic for graceful failover and rebalance when node is stopped or crashes

Test Run Examples

Stop Graceful Failover Test:: https://friendpaste.com/4NniA1sxhHlfq1caYGgu77

Stop Node: Graceful Failover+No add back: https://friendpaste.com/4NniA1sxhHlfq1caYGgnTo

Stop Node: Graceful Failvoer+Delta Add Back Recovery: https://friendpaste.com/4NniA1sxhHlfq1caYGglYJ

Kill Node: Hard Failvoer+full Add Back Recovery: https://friendpaste.com/MMo248klhwC3dz30BiWU3

Change-Id: I13bae9df8436c39ad3ab6077345b019b6d987f36
Reviewed-on: http://review.couchbase.org/40731
Reviewed-by: Parag Agarwal <agarwal.parag@gmail.com>
Tested-by: Parag Agarwal <agarwal.parag@gmail.com>