Enforce a width on a slide.

It was just kind of moving based on the browser window, which was
changing the number of possible columns.  So you wouldn't get a
consistent experience on a narrower browser.  That's nice for reading,
but if you're editing on a narrower browser you don't want to break it
for everybody else.

I think when you want to support mobile you need to make sure that
nobody can drag stuff around.
Ability to assign a perspective.

Well that was painful.  Gridster hijacks the DOM and Ember doesn't know
about DOM changes that it didn't initiate.  Hilarity ensues.  Attribute
bindings aren't two way, it doesn't seem.  It works for form element
values, but maybe they change in a way that is tracked by Ember, while
random data attributes changed by JS code isn't tracked.

Anywho, the way this is done isn't terribly efficient or pretty, but it
works.
Oh, right.  That's why pry don't work so good.