Changed artifact kind to storageType

Do very quick review... tests works so this is just if you have complains...

We have data stored in the current azure table storage. So I'll have to expire all current artifacts before I upgrade... I'll start on that now...

**Note**, version numbering and migration for entities is on my wish list of things that could be nice to have some day. Right now it just crashes if it gets an old entity that doesn't match the declared schema.