CBQE-0: adding code to cancel remaining tasks after test is failed with
timeout error

Change-Id: I09c3f937e5adc8cb2cf50875eb5f2be4d8909cc4
Reviewed-on: http://review.couchbase.org/31817
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>