Adopt to router changes

[samdark]

yiisoft/router#128

Route arguments should be taken from CurrentRoute now, not from request.

[samdark]

Done in general but need to mention it specifically in request-response description and have it more explicit in router.

[rustamwin]

Also need document

• auto response options (take it from README or router)
• locale based URLs https://github.com/yiisoft/demo/pull/422/files