packaging:

- Added script which generates version string based on inserted version number.
- Changed Makefile to include svn revision and branch name in version string if possible.
- Modified build_release-packages.sh to automatically write version string to version management files.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@2768 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534