Seeds: all data of MH products

Now we have all meaningful data from products in the seeds.
However:

- Image should still be stored there as image
- Taxes should be stores as tax group name, not index, which is
  not descriptive.
- Need to check other products/categories related tables.
- Categories have not been even looked at yet.

Signed-off-by: Zeljko <zeljko@zwr.fi>