Overrides getRecordUrl.

Provides correct url information to Omeka helpers.
Use record_url to create url for neatlinetime-json.
Removes some unused code in link_to_timeline helper.
Removes test for deleted function.

Removes the test for neatline_time_display_search_query, which was removed in
3e7de75bfff4eb59eee5f780f7463ad41466d0c7.
Use Omeka helper functions for displaying metadata.

Deprecates the timeline adn link_to_timeline helpers in favor of using Omeka's
helper functions. Updates tests to account for these changes and changes in
previous commits.