Fixes for express definitions.

app.listen is fixed so that it can be called with a port, hostname, and
optional callback without a backlog parameter.

app.listen is fixed so callback parameter is always optional.

CSRF protection middleware definition is fixed so options parameter is
optional.

req.csrfToken method is added since the CSRF protection middleware has
been updated.

express/express.d.ts

@@ -405,6 +405,12 @@ declare module "express" {
             //cookies: { string; remember: boolean; };
             cookies: any;
 
+	    /**
+             * Used to generate an anti-CSRF token.
+             * Placed by the CSRF protection middleware.
+             */
+	    csrfToken(): string;
+
             method: string;
 
             params: any;
@@ -1063,9 +1069,11 @@ declare module "express" {
              *    http.createServer(app).listen(80);
              *    https.createServer({ ... }, app).listen(443);
              */
-            listen(port: number, hostname: string, backlog: number, callback: Function): void;
+            listen(port: number, hostname: string, backlog: number, callback?: Function): void;
+
+            listen(port: number, hostname: string, callback?: Function): void;
 
-            listen(port: number, callback: Function): void;
+            listen(port: number, callback?: Function): void;
 
             listen(path: string, callback?: Function): void;
 
@@ -1471,13 +1479,12 @@ declare module "express" {
         /**
          * Anti CSRF:
          *
-         * CRSF protection middleware.
+         * CSRF protection middleware.
          *
-         * By default this middleware generates a token named "_csrf"
+         * This middleware adds a `req.csrfToken()` function to make a token
          * which should be added to requests which mutate
          * state, within a hidden form field, query-string etc. This
-         * token is validated against the visitor's `req.session._csrf`
-         * property.
+         * token is validated against the visitor's session.
          *
          * The default `value` function checks `req.body` generated
          * by the `bodyParser()` middleware, `req.query` generated
@@ -1488,11 +1495,11 @@ declare module "express" {
          *
          * Options:
          *
-         *    - `value` a function accepting the request, returning the token 
+         *    - `value` a function accepting the request, returning the token
          *
          * @param options
          */
-        export function csrf(options: any): Handler;
+        export function csrf(options?: {value?: Function}): Handler;
 
         /**
          * Directory: