WIP: Everything is broken

We need to switch the parent/child relationships between Yale Containers
to be uni-directional.  Because of a bug in the relationships code, we
can only make that work if "parent" is an array of values.  Maybe that's
OK anyway.

So we need to:

  * Fix the indexer to deal with the arrays
  * Verify that we're seeing the right thing with curl
  * Rework the frontend forms to cope with all of this.