system/messages/messages_*.properties was deleted in upgrading

[Cantor, Scott]

> > > We just have to set some ground rules. The installer won't remove files in
> system/ it doesn't know about, but we don't want to accidentally step on anything either.
> 
> That’s not what it does, but maybe what we should make it do.  I'm sure Scot
> and I will be working this one through...

Obviously I thought that's what it did but I was mistaken. We don't want to have to track the file manifest closely enough so I doubt we want to change what it's doing.

In the end, not deleting them there would have the same impact as putting them in messages/ to begin with, either would prevent them from being overwritten if they needed to be.

Without installer support for the actual concept of a translation, I think they have to go in messages/

Otherwise it could be the installer's job to install some set of the "current" translations when system/ gets recreated and then it wouldn't really matter where they went.

We could also just take what exists and start checking them in, and if they fall out of date, it's no worse than not having them.

-- Scott