Code cleanup for vlserver

Code cleanup for vlserver

Move the cnvldb.h include so it's after vlserver.h
Don't define MAXSERVERS in cnvldb.h (it's already defined elsewhere)
Cast nvldbentry(s) to vldbentry to avoid warnings from display_entry
Volume IDs are unsigned
Use var[0]='\0' rather than sprintf(var, "");

Reviewed-on: http://gerrit.openafs.org/237
Tested-by: Marc Dionne <marc.c.dionne@gmail.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>