Add first batch of skeleton classes for new Http client.
Start adding FormData code + tests.
Add basic file support for FormData.

I have to double check the requirements around other
headers like Content-Type and Content-Transfer-Type.
Implement the rest of file support.
Add stubs/incomplete code for Request/Response.
Add incomplete send() method to Adapter.
Start implementing request building.

* Add highlevel tests for GET.
* Add tests for url building.
Start adding tests for Request.
Set headers if available.
Implement Request::header()
Implement more parts of the Request class.
Add Request::cookie()
Add tests for building requests with headers/cookies.
Starting to build out Stream adapter.
Add FormData::addMany()

This makes integration with the client simpler.
Implement setting content for a request.
Add SSL option handling.
Expand doc blocks.
Build prototype of running requests.
Starting to implement Response object.