Add support for server-side basic auth

This enables basic auth on the Node server -- so that in order to
access I/O Docs (http://localhost:3000, for example), you will need to
enter in a username and password.  This should not be confused with
adding basic auth support while making API calls within the I/O Docs
configured API.

README.md

@@ -56,6 +56,16 @@ RUNNING I/O DOCS
 2. node ./app.js
 3. Point your browser to: [http://localhost:3000](http://localhost:3000)
 
+
+BASIC AUTH FOR SERVER
+---------------------
+Enabling HTTP basic authentication on the server is simple. By default, the username and password values are empty ("").
+
+1. Open up *config.json*
+2. Navigate down to the *basicAuth* object
+3. Add values for username and password within the object
+
+
 QUICK API CONFIGURATION EXAMPLE
 -------------------------------
 Adding an API to the I/O Docs configuration is relatively simple.

app.js

@@ -105,6 +105,14 @@ app.configure(function() {
         })
     }));
 
+    // Global basic authentication on server (applied if configured)
+    if (config.basicAuth && config.basicAuth.username && config.basicAuth.password) {
+        app.use(express.basicAuth(function(user, pass, callback) {
+            var result = (user === config.basicAuth.username && pass === config.basicAuth.password);
+            callback(null /* error */, result);
+        }));
+    }
+
     app.use(app.router);
 
     app.use(express.static(__dirname + '/public'));

config.json.sample

@@ -4,6 +4,10 @@
     "port" : 3000,
     "debug" : false,
     "sessionSecret" : "12345",
+    "basicAuth": {
+        "username":"",
+        "password":""
+    },
     "redis" : {
                 "host" : "localhost",
                 "port" : 6379,