Refactor item page js

Significant updates here to how an item is handled. Removed functionality of downloads #59 and table inspection #60 but created feature tickets for them. Left old js plugin in for reference but `map-view.js` should be removed when those tickets are completed.

Now a geoblacklight application can be configured to it's host institution using the rails_config gem. This settings file should be automatically created at `config/settings.yml` when the generator is run.