implement cookies support within `net\http\Request` and add tests to demonstrate
ensure `Content-Length` header is set for all POST and PUT requests, even when body length is zero.
allow for multiple headers with the same key when parsing a response message (i.e. Set-Cookie)
Mocker issues.
Fix `Mocker` accidentally calling php magic set/get methods.

When creating a new `Document` it delegated `parent` to magic methods, when it should have been a property of the class itself. This was fixed by explicitly adding `parent` as a property of `MockDelegate`.

The second issue is when a class uses `get_called_class()` to generate a new object. Since this will return `MockDelegate` which shouldn't be called directly. This was solved by allowing it to be called directly. It will now generate a new `Mock` stack and replace the existing `MockDelegate` with itself.
Merge pull request #900 from BlaineSch/bug/mocker

Bug/mocker
implement cookies support within `net\http\Response` and add tests to demonstrate
implement `\action\Request::headers()` and `\action\Request::to('string')` to behave as expected in correlation with their counterparts in `\net\http\Request`
simplify `\action\Response::render()` and header output; move shorthand header magic to overloaded `header()`
Merge pull request #902 from pixelcog/request-response-cookies

Improve Li3 Request/Response Classes