CORE-344 adding styling for dropdown and JS function to automaticaly cho...

CORE-344 adding styling for dropdown and JS function to automaticaly choose position
This code should be in `CMS.Controllers.InnerNav` which is in `dashboard_controller.js`. Try to avoid using `application.js` as it is already too cluttered and needs to be cleaned out.

Let me know if you need help adding this to InnerNav controller.