87 multiple download links

[aergul]

@torrin47 please review and merge this PR if all look good.

Deployment instructions for this PR:

• Stop Tomcat
• Copy updated files to their respective locations on the target server
• Edit additional xxx-indexables.xml files to capture multiple links as resource URLs similar to dcat-indexables.xml
• Delete lucene indexes
• Temporarily change, in gpt.xml, the time when index synchronization occurs so that it kicks in soon after Tomcat start
• Start Tomcat
• Wait for syncronization to kick in and then complete.
• Verify new behavior in search results and details pages
• Revert synchronization time back to regularly scheduled time in gpt.xml
• Check into the repository all updated indexables files

[torrin47]

So resource links are being correctly displayed in the REST endpoint (and the details pages), but the extra Esri links (kml, nmf, etc) don't seem to be suppressed:

And the results on the main search page also show the additional links, but in a different layout:

Always thought it was tacky that the search page uses a different mechanism to get the records and doesn't just display the standard REST results. No dogfooding for geoportal server I guess. Thoughts?

Also not sure how the "Preview" button snuck back in, but we definitely don't want that one, it's useless. Thanks!