Add helper methods for rendering MODS names...
...and use in mods upper metadata section.
Link subjects and render hierarchically.
Add helper to link URLs and email addresses from mods strings.
Merge pull request #214 from sul-dlss/mods-config

Update mods parsing code in lieu of using ModsDisplay configuration.
Add SearchQueryModifier class and use logic to render additional results block partial.
Modify zero results page to use SearchQueryModifier.