More multi-user stuff:

- New (hidden) isUserRunning() API.
- Maintain LRU list of visited users.
- New FLAG_IS_DATA_ONLY for ApplicationInfo.
- Clean up pending intent records when force-stopping a user (or package).
  (Also fixes bug #6880627: PendingIntent.getService() returns stale
  intent of force stopped app)
- Fix force-stopping when installing an app to do the force-stop across
  all users for that app.
- When selecting which processes to kill during a force stop, do this
  based on the actual packages loaded in the process, not just process
  name matching.
- You can now use --user option in am when starting activities, services,
  and instrumentation.
- The am --user option accepts "current" and "all" as arguments.
- The pm uninstall command now uninstalls for all users, so it matches
  the semantics of the install command.
- PhoneWindowManager now explicitly says to start home in the current
  user.
- Activity manager call to retrieve the MIME type from a content provider
  now takes a user argument, so it will direct this to the proper user.
- The package manager uninstall paths are now implemented around
  PackageSetting, not PackageParser.Package.  This allows them to work
  even if the application's apk has been removed (in which case it only
  exists as a PackageSetting, not the PackageParser.Package parsed from
  the apk).

Change-Id: I3522f6fcf32603090bd6e01cc90ce70b6c5aae40