More Boostrap 2 -> 3 upgrades.

Fixes #528, #508
See the mismatch here: https://github.com/projecthydra/sufia/blob/c3fe200c577055439432a03d42171a7ee57a9caf/app/views/users/edit.html.erb#L18
https://github.com/projecthydra/sufia/blob/c3fe200c577055439432a03d42171a7ee57a9caf/app/controllers/concerns/sufia/users_controller_behavior.rb#L54