ContainerBlockAdmin is missing block specific fields

[wouterj]

This admin should be able to set child blocks (and create new child blocks). At the moment, only the parent and node name are configurable in the admin panel.

[ElectricMaxxx]

Setting a child would mean to move an existing one under the current one?

[wouterj]

Not very sure how to do this. I think for 1.0, we simply have to disable the container block admin. In 1.1, we can work on #47 and probably fix this one as well then.