CBQE-0: add details logs in log_command_output

Change-Id: Ic9775584db120f5102c69afb4962214cb4ce61a9
Reviewed-on: http://review.couchbase.org/30379
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>