[Issue995] Prettify bug set view, update migrations

Edited: See https://openhatch.org/bugs/file685/bugset-fix.png for preview.
Does that actually work the way it should? `bug.skills` returns a m2m controller in the shell, so I'd assume that was always true. `count` seems to make sense. I'm a fan of `first` but it's not supported in this version of Django.