CBLT-309:  also upload build logs to S3

Change-Id: Ie51684c1827e2ac711547291b3381785c6b8d44f
Reviewed-on: http://review.couchbase.org/37758
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>