Work on issue #18572506: AppOps in-memory state is invalid after...

...uninstalling updates to a system app

Things seem to be working fine, however we were not as aggressive at
writing out the current state in this case as we probably should be.

Also introduce more features to the appops command, which are useful
for testing this.

Change-Id: I177a9cc0e16e98b76fee0d052d742e06842bb3f9