bug 881629 - report dropdown should not reset version

I think this is worth taking as-is and makes life better (and removes some old legacy code to boot), but see https://bugzilla.mozilla.org/show_bug.cgi?id=881629#c1 for a more complete explanation (there are some caveats due to a few non-standard reports).

@jezdez and @peterbe - is there a better way than what I've done in the template here? It works and is clear (IMHO) but is a bit verbose.