jensvfischer_benchmark/servers: Some small name changes.

Change the unit naming for bytes to use the IEC binary prefixes (MiB instead of MB etc).
Add static for the base volume name used in the benchmarks.

git-svn-id: https://xtreemfs.googlecode.com/svn/branches/jensvfischer_benchmark@3713 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534