render_thumbnail helper links to catalog show page.  Fixes #212.
Removed overriding blacklight_helper module to revert to default link_to_document behavior.
Fixes #210.
Removed #object_children_nav_item method b/c unused.
Fixes #201.
Removed #object_has_preservation_events? -- use object.has_preservation_events?
Fixes #200.
Removed #title_display_solr_value(solr_doc) -- use solr_doc.title
Fixes #199.