CBLT-202:  only copy release/*.*

Change-Id: Ide7ab69fe2157eecc6183a3f63e3ea4f7159918b
Reviewed-on: http://review.couchbase.org/41322
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>