- made generate_uuid work with any uuidgen in $PATH

- made the server packages require uuidgen for proper UUIDs
- made the postinstall script work with client-only packages
- allow non-SUSE rpm distributions to properly stop and restart the services on uninstall/update
- write the postinstall script INTO the rpm spec file and debian postinstall scripts instead (this is better than just using it since it is not available inside the client packages)

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@1643 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534