Add TODO for persisting cookies in responses.
Fix constructor options completely overwriting defaults.

Constructor arguments should augment not replace the defaults.
Add support for handling redirects.

Transport adapters should always return an array of responses,
in the order they occured. This allows redirects to happen,
and will allow the Client object to maintain cookies per host.
When doing https requests you have to use 'http'

You have to always use 'http' as the context name. It seems that
PHP fails to recognize 'https', and wants 'http' instead.