Add option for purge helper to delete files as root

[GoogleCodeExporter]

Sometimes users have files that are their responsibility in their home 
directory that they may not 
have permission to delete, e.g. files that need to be writeable by the user 
running the web server. It 
may be desirable to delete these files anyway when a home directory is purged. 

I'm not certain if implementing this feature really is all that great of an 
idea though, because 
deleting everything as root has a lot of potential to cause damage. An 
alternative solution may be 
to specify a list of other users to try dropping privileges to if the first 
deletion as the user itself 
fails.

Original issue reported on code.google.com by nick.bar...@gmail.com on 19 Dec 2008 at 1:31