Clean up the AngularJS application

[mstine]

This code is currently in springbox-api-gateway/src/main/resources/static/js/hello.js.

Should be given a proper name obviously.

Also - I am not a strong JS or Angular developer, so this could use some general love from @scottfrederick.

[scottfrederick]

• rename hello.js to app.js
• rename angular app from hello to springbox
• split angular controllers into separate .js files that match partials that use them