Remove the date from man pages

It's not something we're keeping up to date anyway.
diff --git a/unix/vncserver.man b/unix/vncserver.man
index 413da2a..dceaa79 100644
--- a/unix/vncserver.man
+++ b/unix/vncserver.man
@@ -1,4 +1,4 @@
-.TH vncserver 1 "13 Mar 2011" "TigerVNC" "Virtual Network Computing"
+.TH vncserver 1 "" "TigerVNC" "Virtual Network Computing"
 .SH NAME
 vncserver \- start or stop a VNC server
 .SH SYNOPSIS