Improve search UX

[jeancochrane]

Overview

Three small fixes to improve the search UX:

• Fix a bug related to facet results (filter list no showing all possibilities #59)
• Style visited search result links (visually differentiate visited documents from those not visited #56)
• Provide a 'back' button to the search page on detail pages (return to previous view/line of search results instead of top of page #55)

Testing Instructions

• Visit http://localhost:8000/flatdrawings/search/?q=palos&selected_facets=area_exact%3A23 and confirm you see 9 as an option in the Section facets (filter list no showing all possibilities #59)
• Choose View details for a flat drawing and test return to previous view/line of search results instead of top of page #55:
  • Confirm you see a Back to search results link at the top of the page
  • Copy the URL to this detail page for later
  • Click the Back to search results button
  • Confirm you get taken back to the same search, and directed to the row you clicked on your search
• Confirm that the View details link for the flat drawing you viewed is colored purple instead of blue
• Go back to the homepage at http://localhost:8000, paste the URL to the flat drawing detail page you copied earlier into the address bar, and navigate to the page
  • Confirm that you do not see a Back to search results link at the top of the page

[derekeder]

all tests work as expected!