Rework how the page gets wrapped

[laryn]

Early on as I was experimenting, it seemed some pages needed to be wrapped with the class gin-layer-wrapper to add a background, rounded corners, etc. -- but other pages didn't, such as the main admin content page where the view itself has a background, rounded corners, etc. and I didn't want to double up on those visuals.

At this point my makeshift hardcoded list of pages that need to be wrapped is getting out of control so I'm going to rethink how I'm doing that.