[Modules] Add buttons that stay on screen as you scroll

[rshortphs]

It would be very helpful if the "+" buttons for adding items into modules and other things stayed on the page with me as I scrolled down the page. Some of my modules get lengthy and to have to scroll back up to add an activity and then scroll back up again to add other things gets time consuming. This is the same all around the site, for instance, the "+ question" feature in quizzes. As my list of questions gets longer I spend a lot of time having to scroll whereas if the button scrolled with me, anticipating I'll be adding more questions, would save time.