Configure collection_titles_ssim as the default collection field; deprecate collection_with_title

[corylown]

Fixes #810

After this is deployed to production I will run a script from the Rails console to update all the custom configurations to use the new field:

Spotlight::BlacklightConfiguration.find_each do |config|
  old_index_config = config.index_fields['collection_with_title'] || {"label"=>"Collection", "list"=>true, "gallery"=>false, "heatmaps"=>true, "masonry"=>false, "slideshow"=>false, "show"=>true, "enabled"=>true}
  config.update(
    index_fields: config.index_fields.merge({
      'collection_with_title' => { 'enabled' => false, 'show' => false },
      'collection_titles_ssim' => old_index_config
    })
  ) unless config.index_fields.blank?
  
  old_facet_config = config.facet_fields['collection_with_title'] || {"show"=>true, "label"=>"Collection", "sort"=>"count"}
  config.update(
    facet_fields: config.facet_fields.merge({
      'collection_with_title' => { 'show' => false },
      'collection_titles_ssim' => old_facet_config
    })
  ) unless config.facet_fields.blank?
end

Some exhibits will need to be manually configured either because they don't set a custom configuration or they need to continue to use the deprecated collection field (because they can't be re-indexed):

Manually configure to use the deprecated facet field:

• views-portraying-place-space (facet and index)
• gordon-maps (facet and index)
• chinese-ngos (index only, facet off)

Manually configure facet to use new field and turn off old field because they do no have a configuration set:

• ai
• conservation
• awards
• calligraphy
• seaside
• dataviz