read version of active app_process directly from the file (instead of using the strings command)

Also reduce the loading time of the InstallerFragment drastically (from 4
to 1.5 seconds in my tests!) by adding a simple check. Wow, I should use
DDMS more often, especially for UI releated stuff!
Pass user ID from Java to the installer script

Should avoid problems where /data/system/packages.list is corrupted on the
system. Also reduces the size of busybox by a few kB, which is now without
grep and cut.