Highlighting/snippets

[escowles]

It's not always obvious why some search results are retrieved, so it might be nice to show snippets and/or highlighting to make this clearer. However, we don't want to clutter or further bulk up the search results. So options we discussed at the 01/23/2018 LISSC meeting included:

• allow showing snippets/highlighting on search results (via a button on the search results somewhere)
• allow showing snippest/highlighting on item pages (again, via a button, maybe with the staff view)
• use modest color/font differences instead of bold yellow highlighting
• show snippets in hover text

[christinach]

Closing in favor of pulibrary/pul_solr#388