Fixes stamp_availability to work on topic tree data also.
Refactors backbone into own fle_utils app to add helper functions.
Inherits from BaseView class for ContentBaseView.
Uses listenToDOM method for event listeners on DOM elements.
Adds sidebar styling for Document entries.
Fixes integration bugs for listenToDOM method for audio and PDF views.
Fixes client side routing when a content view is rendered.
Resolves #2456.
add back the search bar