improve creation of OpenVZ archive

when create a archive the container config will be the fist file in archive.
This is useful if we recover the archive.

PVE/VZDump/OpenVZ.pm

@@ -253,7 +253,7 @@ sub archive {
     my $cmd = "(";
 
     $cmd .= "cd $snapdir;find . $findargs|sed 's/\\\\/\\\\\\\\/g'|";
-    $cmd .= "tar cpf - $taropts --null -T -";
+    $cmd .= "tar cpf - $taropts ./etc/vzdump/vps.conf --null -T -";
     my $bwl = $opts->{bwlimit}*1024; # bandwidth limit for cstream
     $cmd .= "|cstream -t $bwl" if $opts->{bwlimit};
     $cmd .= "|$comp" if $comp;