By TravisCarden: Fixed coding standards issues.
By TravisCarden: Changed route _content to _controller per #2378809.
By TravisCarden: Converted to new Unicode component per #1992584.
By TravisCarden: Changed type hinting of $form_state per #2310411.
By TravisCarden: Updated access checking logic per #2337377.
By TravisCarden: Replaced current_path() with <current> route per #2382211.
By TravisCarden: Converted CSS and JS to libraries per #2379475.
By TravisCarden: Replaced calls to deprecated drupal_render() with renderer service.