Let's add ability to use v1 API .

Due to incompatibility of http-server versions v1 API would work via adapter layer, like here.

The incompatibility list:

• splitted router and server objects in http v2, in http v1 they are parts of one object
• before_dispatch and after_dispatch hooks are not supported by default
• headers, path, peer, method, proto, query in http v1 are request's object fields, but they are methods in http v2
• handler option was removed from v2

Also user should get a warning, if he uses v1 API. Both versions' usage should be prohibited, user should use only v2 API or v1 API.