wait for first checkbox to be done before continuing

I believe the best way to fix the problem we are having with select all

Closes #875

I also have another solution that doesn't quite work here: https://github.com/sul-dlss/SearchWorks/tree/select-all-fix

The problem with doing this server side, is that BL plugin that creates the interactivity keeps track of state separately and only looks for it once (on instantiation). https://github.com/projectblacklight/blacklight/blob/master/app/assets/javascripts/blacklight/checkbox_submit.js#L108

I believe this is the best way to do this, but am open to other ideas.