Use symfony/web-server-bundle instead of the WebServerManager homemade

[maidmaid]

By using symfony/web-server-bundle :

• a part of Add support of router script #106 becomes obsolete because the router script support already exists in this package,
• the same about Change default port to 9080 #105 because this package auto discovers a correct port.

Ok, it is a bundle at the moment but not a component, but it is from the same Symfony family. Very probably, there will be new others needs which will be requested and already covered by this package. Why not use it now ?

[dunglas]

Why not, as long as it keeps working without a dependency to framework-bundle.