Public lazy loading

A bunch of commits around making the public interface lazily load tree structures.  Some notes:

  * We no longer need to index the whole tree structure for resources or digital objects.  We still do it for classifications, but they're much smaller.

  * The tree_view documents in Solr weren't being correctly deleted from the index, so marking something as "unpublished" wasn't taking effect.  Fixed that by quoting the URIs before sending them in the delete query.

  * The "Components" section in resources/digital objects is now fully lazy and just shows the tree structure.  A separate story will address adding a "search in record" function.