3.0 simplify api

Docs for
- https://github.com/cakephp/cakephp/pull/3272 [merged]
- https://github.com/cakephp/cakephp/pull/3270 [merged]
- https://github.com/cakephp/cakephp/pull/3268 [merged]
- https://github.com/cakephp/cakephp/pull/3274 [merged]