Added the possibility to add a chain of request handlers for a certain route

[SamVerschueren]

As described in https://github.com/dartist/express/issues/16 I added the possibility to register a chain of request handlers. This allows the developer to use little pieces of middleware.

// Controllers
HomeController home = new HomeController();

// Middlewares
AuthMiddleware auth = new AuthMiddleware();

var app = new Express();
// The old way but still working with this update
app.get('/', home.index);

// The way it could be done with middleware
app.get('/users').then(auth.isSignedIn).then(home.users);

Because of the changes, it's not possible to chain them like this

var app = new Express();
app.get('/', home.index)
     ..get('/users', home.users);

If this pull request is accepted, I will update the README documentation.

[mythz]

Hi Sam,

You may have a dirty fork because GitHub wont allow automatically merging this pull-request. I suggest doing a clean pull before resubmitting the pull-request.

Change looks good tho! Allows better customization whilst Dart's cascade operator retains the ability to chain routes as before.

[SamVerschueren]

That's odd, thought I had the latest code. Will clean pull and add the changes again.

Will change the readme as well then with the latest updates.

[SamVerschueren]

This request can be denied and issue https://github.com/dartist/express/issues/16 can be closed.