Remove duplicate header

And provide a slightly more informative prompt

core/modules/commands/server.js

@@ -95,9 +95,8 @@ SimpleServer.prototype.listen = function(port) {
 		if(username && password) {
 			// Check they match
 			if(self.checkCredentials(request,username,password) !== "ALLOWED") {
-				response.setHeader("WWW-Authenticate", 'Basic realm="Admin Area"');
 				response.writeHead(401,"Authentication required",{
-					"WWW-Authenticate": 'Basic realm="TiddlyWiki5"'
+					"WWW-Authenticate": 'Basic realm="Please provide your username and password to login to TiddlyWiki5"'
 				});
 				response.end();
 				return;