Use WHATWG URL for request.url

[kanongil]

I had a look into what it would take to update hapi to use the WHATWG URL API since Url.parse() is being deprecated, and node 8 already supports the replacement API.

As far as I can tell, the only directly affected api is the request.url property, and the setUrl() method.

PR details:

• All usage of old style URL objects, and Url.parse() has been replaced with the new URL API. There is no legacy support.
• Added a route.queryParser option to retain ability to customize the query parsing. The return value is validated so that request.query will always be an object.
• request.url property is no longer relative, since the URL constructor won't create relative URLs.
• setUrl throws a badRequest error if the URL parsing fails.

[kanongil]

Note: We could probably remove the request.info.hostname and request.info.host fields, since they are now always available on request.url.

[hueniverse]

I changed it to be more consistent and less flexible.