Make hippogallery:stdImageGallery and hippogallery:stdAssetGallery orderable by default

Stephan,

Please adjust the default settings for hippogallery:stdAssetGallery & hippogallery:stdImageGallery and make them orderable by default.

Note that the ordering on root level might not be available in the UI at this point.
For now it's ok if we (prof. services) could reshuffle imageGalleries or assetGalleries via the console