packaging:

- Added URL: tag since rpmlint complained about it.
- Added permissions and owner/group for /etc/xos/xtreemfs/default_dir.
- Added fourth parameter for %defattr directive.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@3492 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534