CBQE-0: more logs if init RemoteMachineShellConnection failed

Change-Id: Ifb3efdf9ea6f3362b060ffdb58a14acee28eeca9
Reviewed-on: http://review.couchbase.org/27226
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>