Enhance RTA triggering in packaging scripts

Enable RTA triggering for online repository builds as well.
Put common constants into common file which can be included across
packaging scripts.

Change-Id: Iedb69a174c078486e7a919fff337e6b247e6b6e3
Reviewed-by: Samuli Piippo <samuli.piippo@digia.com>
Reviewed-by: Antti Kokko <antti.kokko@digia.com>