Added instructions for setting up captcha in an obviously named file.

webclient/CAPTCHA_SETUP

@@ -0,0 +1,46 @@
+Captcha can be enabled for this web client / home server. This file explains how to do that.
+The captcha mechanism used is Google's ReCaptcha. This requires API keys from Google.
+
+Getting keys
+------------
+Requires a public/private key pair from:
+
+https://developers.google.com/recaptcha/
+
+
+Setting Private ReCaptcha Key
+-----------------------------
+The private key is a config option on the home server config. If it is not 
+visible, you can generate it via --generate-config. Set the following value:
+
+  recaptcha_private_key: YOUR_PRIVATE_KEY
+  
+In addition, you MUST enable captchas via:
+
+  enable_registration_captcha: true
+
+Setting Public ReCaptcha Key
+----------------------------
+The web client will look for the global variable webClientConfig for config 
+options. You should put your ReCaptcha public key there like so:
+
+webClientConfig = {
+    useCaptcha: true,
+    recaptcha_public_key: "YOUR_PUBLIC_KEY"
+}
+
+This should be put in webclient/config.js which is already .gitignored, rather 
+than in the web client source files. You MUST set useCaptcha to true else a
+ReCaptcha widget will not be generated.
+
+Configuring IP used for auth
+----------------------------
+The ReCaptcha API requires that the IP address of the user who solved the
+captcha is sent. If the client is connecting through a proxy or load balancer,
+it may be required to use the X-Forwarded-For (XFF) header instead of the origin
+IP address. This can be configured as an option on the home server like so:
+
+  captcha_ip_origin_is_x_forwarded: true
+
+
+

webclient/README

@@ -11,14 +11,3 @@ Then, open this URL in a WEB browser::
     http://127.0.0.1:8000/
 
 
-ReCaptcha Keys
---------------
-The web client will look for the global variable webClientConfig for config options. You should
-put your ReCaptcha public key there like so:
-
-webClientConfig = {
-        recaptcha_public_key: "YOUR_PUBLIC_KEY"
-}
-
-This should be put in webclient/config.js which is already .gitignored, rather than in the web
-client source files.

webclient/login/register-controller.js

@@ -19,7 +19,11 @@ angular.module('RegisterController', ['matrixService'])
                                     function($scope, $rootScope, $location, matrixService, eventStreamService) {
     'use strict';
     
+    var config = window.webClientConfig;
     var useCaptcha = true;
+    if (config !== undefined) {
+        useCaptcha = config.useCaptcha;
+    }
     
     // FIXME: factor out duplication with login-controller.js
     
@@ -132,6 +136,10 @@ angular.module('RegisterController', ['matrixService'])
                     else if (error.data.errcode == "M_CAPTCHA_INVALID") {
                         $scope.feedback = "Failed captcha.";
                     }
+                    else if (error.data.errcode == "M_CAPTCHA_NEEDED") {
+                        $scope.feedback = "Captcha is required on this home " +
+                                          "server.";
+                    }
                 }
                 else if (error.status === 0) {
                     $scope.feedback = "Unable to talk to the server.";