Add optional route parameters

[franklinkim]

Allow for optional route parameters and preserve methods default definitions!

The syntax might look like the one from Backbone.js:

class MyRouter extends \Foomo\Router
{
  public function __construct()
  {
    parent::__construct();

    $this->addRoutes(array(
      '/myRoute(/:param1)(/:param2)' => 'myRoute',
    ));

    public function myRoute($param1='foo', $param2='bar')
    {
      // ...
    }
  }
}