Define dedicated package for HTTP server.

Server lives on its own domain, with the default server being HTTP.

Use X-Original-Method for forcing a POST method to become a QUERY
method.

Prepare tests for supporting QUERY method.

Unify returning of Accept-Post and Accept-Patch items.

Put data source to its own package.

Prepare project for multiple packages.

Include tests for emplace, modify fallback content negotiation logic.

Allow PATCH method to use JSON Patch.

Decouple tests from data source.

Decouple tests from data source.

Add tests related to error handling.