Fix assignments acting flakey after create.

Well that was a really fun bug.  Since it's completely undocumented, you
have to guess, and it jukes you by working 95% of the way with one
naming convention and 100% the other way.  The assignment was getting
persisted properly, but wasn't picking up its new ID after the AJAX call
came back.  Wow.
Sideload assignment configuration with perspectives.

It keeps it from making a second request to get the configuration for
the assignment that it just created.  That's nice and all, but I was
actually just trying to troubleshoot this godawful issue where new
assignments are causing JS errors for every data update thereafter.
It's when it's rendering the template, but other than that I can't
figure it out.  The stacktrace is absolutely useless.