Snapshot file name is not in format InvariantCulture

[nscheibe]

The snapshot file name is culture info sensitive. This means the file names of the snapshots can be different on systems with different culture info configured (de, en, ch....). This should not be, because the name of the snapshot file must be always the same, not depending on the configured system.

I propose to have the snapshot name always in the culture info "invariant" (CultureInfo.InvariantCulture). Therefore the name of the snapshot is everywhere the same.