bug #102657: RFE: Move default block size from tape server to the vdqm and/or vmgr

Increased the reply buffer used when servicing VMGR_QRYTAPEBLKSIZE requests.  The buffer should have been at least 181 (177 + 4 new bytes) and it was still only 177 bytes.  It is now 256 bytes to be on the safe side.