* removed the Kernel::registerRoutes() method
* added a router entry in <web:config> (replaces the registerRoutes() method)
<web:config>
<web:router resource="%kernel.root_dir%/config/routing.xml" />
</web:config>
* refactored routing configuration in its own routing.xml file (leverages the new routing component API),
which is loaded only if <web:router> is defined in the configuration
