Fix 'dcache version' regression

We recently decoupled version number handling from SVN. That change introduced
a regression in that the 'dcache version' command no longer prints the
version number of dCache.

Target: trunk
Require-notes: no
Require-book: no
Acked-by: Christian Bernardt <christian.bernardt@desy.de>
Patch: http://rb.dcache.org/r/5445/