Re-write the Sir-Trevor Search Results block.
Move _prefixes method into PagesController now that we're pulling search results into about and feature pages.
Don't use block variable name as it may be confused as an actual block.
Use #select! instead of !reject for better readability.
Add flash-style warning when a browse category in a search widget has no documents.
Add controller spec for BlacklightConfigurationsController#available_configurations
Move get_search_results from search results widget to a helper method.