packaging:

- Added /etc/xos/xtreemfs/default_dir to xtreemfs-tools package.
- RPM: Create log directory /var/log/xtreemfs during %install.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@3490 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534