make sure that product.type is an array

Mark the property product.type as StringList and make sure that it
ends up as array in JavaScript. This saves us from conversions when
using it. Also react correctly on the values applicationbundle and
frameworkbundle.

Change-Id: I47d35beca60ba37644bc012ff55fe1b3df4cdf45
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>