Toggle sidebar visibility directly from the angularjs controller, instead of from inside some services.

This means better separation of concerns and better readability.
Fixed error in CSS nesting. Also, the main app menu in smartphones now has a drop shadow and a subtle gradient, to better distinguish it from the background.
In smartphone screens, remove the horizontal scrollbar from the app menu. Also, the user dropdown only has a 0 margin-right (instead of the default -15px) in sm and larger screens, to leave some space to the edge of the screen. For smaller (smartphone-sized) screens, the navbar buttons are collapsed into the app menu, and we want entries there to be full width without margins; therefore the -15px margin-right is useful there to compensate the 15px margin-right of the enveloping element.