packaging:

- Do no longer copy postinstall_setup.sh to the system.
- RPM: No longer using %_libdir macro since it did not evaluate to /var/lib. Hardcoding /var/lib/xtreemfs paths now.
- RPM: Owning group of /etc/xos/xtreemfs/default_dir is no longer set to "xtreemfs".

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@3508 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534