Facet fix (with some utility methods)

Please feel free to pull the changes to the catalog_controller into your repo.  There are corresponding changes to the imls-solr repo, under a similar request title.

The changes to xml_importer may be of interest: they are there to facilitate troubleshooting.  The existing importer simply channels data from the files read to the index.  Here you have two methods (c&p from their cousins) that return a solr object that can be inspected, or saved to disk.  Perhaps this will prove useful for an admin.