DDF-669 DDF-670 DDF-682

DDF-670 - Restyles the admin application modules.  Setup initial application selection page for Jeren and Sam's work.

DDF-669 - Created Feature management backend API and Feature UI via
config plugin.

DDF-682 Created configuration plugin API framework.  Adjusted
configuration UI to work within a Configuration Plugin.
If the app show state was in the model, you could handle this in the template.  You can override the serializeData method and extend the model to include it for use in the template.  See following example.

https://github.com/codice/ddf-ui/blob/26f343bbb509214e5dee752147f38842c36b0642/search-ui/standard/src/main/webapp/js/view/MetacardList.view.js#L236-L238