CBQE-2476 add ip in error to show which vm failed to
connect using SSH

Change-Id: Ib19b7e7ae55cf61e016826cb249b433e28940dd5
Reviewed-on: http://review.couchbase.org/43142
Reviewed-by: Thuan Nguyen <soccon@gmail.com>
Tested-by: Thuan Nguyen <soccon@gmail.com>