Added proceedings info when missing journal info. Refs #1288

- Added support for a :suppressed_by option when defining which
  solr fields to show in catalog controller. This is used to avoid
  rendering certain fields when other certain fields are available.
- Added a render_conference_info_index helper to render conference
  info. This just calls some of the methods used by the journal
  rendering and currently it doesn't do any toc related stuff.