can't untar archiva with cygwin tar 1.18

[Dan Fabulich]

I'm on Windows XP.  Using cygwin tar 1.18, I find that I can't untar 
archiva; I get "A lone zero block at 49260".  I've filed it as MRM-671.

I've found the zip version, and I'm going to use it.  But I've filed 
MRM-672 that the zip version should be more visible, because tar isn't 
very standardized across OSes...  Linux tar can easily create archives 
that Cygwin tar won't extract, Solaris tar can get confused by long file 
names in GNU tar files, etc.

-Dan