Clear referenced paks when disconnecting

After playing Team Arena, if you switch to Q3A and try to play a demo with
cl_allowDownload enabled it would print "Need Paks: blah blah" and not play the demo.

code/client/cl_main.c

@@ -1457,6 +1457,7 @@ void CL_Disconnect( qboolean showMainMenu ) {
 	
 	// Remove pure paks
 	FS_PureServerSetLoadedPaks("", "");
+	FS_PureServerSetReferencedPaks( "", "" );
 	
 	CL_ClearState ();