CBQE-0 add wait time after start cb server

Change-Id: I8a9b427363b4d26bee4a084fdced3934c7aeee2d
Reviewed-on: http://review.couchbase.org/40428
Reviewed-by: Thuan Nguyen <soccon@gmail.com>
Tested-by: Thuan Nguyen <soccon@gmail.com>