CBQE-0: add elapsedTime to output

Change-Id: I242db197aaa3d088f9ba52cb8a9adc2755000ad1
Reviewed-on: http://review.couchbase.org/42527
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Tested-by: Iryna Mironava <irynamironava@yandex.ru>