CBLT-179:  CURL_CMD="curl --fail --retry 5 --silent --show-error"

Change-Id: Ia1c5f0399eaa1bb974644330f48a3016caa7d116
Reviewed-on: http://review.couchbase.org/36531
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>