Generic upgrade hook to handle version skew

[droos]

When the application updates itself, but the old RMS is still lying around, the old RMS might not be 100% readable by the new application. We need a hook that allows us to perform any necessary upgrades on existing RMS data.

Probably goes something like this: old version stored in RMS every time the app runs, checks its version against RMS if they differ, run the upgrade code (which may differ based on how old the previous version is)