Refactor initial cookies
Refactor working path/method

Working path/method/format is now *always* Request#path/method/format.
This means when rerouting a request, the value of Request#path, etc
will change.

Previous paths/methods/formats can be acessed through the
paths/methods/formats accessors on Request. There is also a
`first_path/method/format` convenience method for getting the first, or
original, value.