Replace prefs tabs with select menu in mobile view

Replace prefs tabs with select menu in mobile view

There are too many account preference tabs to display cleanly on a small
screen resolution, so let's replace them with a select menu for
navigation. At the same time, we remove hardcoded values used for the
navigation tabs so that we do not need to maintain links/labels for the
menus in two different places.

Signed-off-by: Kathy Lussier <klussier@masslnc.org>
Signed-off-by: Lebbeous Fogle-Weekley <lebbeous@esilibrary.com>
Signed-off-by: Dan Wells <dbw2@calvin.edu>