client:

- Ported xtfs_snap functionality to xtfsutil.
- xtfsutil: Fixed missing initialization of class members as reported by Eclipse Juno C++ code analysis.
- xtfsutil: Outputs correct error now if a client does not know a certain operation.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@3289 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534