`Request` is a wrapper around a WSGI environment.  This wrapper itself
doesn't hold any state, which is why it is just a "wrapper".  Because
it has no state, different instances created from the same WSGI
environment are indistinguishable.

Setup just involves passing it an environment::

    >>> from testrunner import make_environ
    >>> env = make_environ(path_info='/foo', method='POST',
    ...                    body='name=Bob', environ={})
    >>> from requestobj import Request
    >>> req = Request(env)

It provides some methods::

    >>> req.params
    {'name': 'Bob'}
    >>> req.path_info, req.method
    ('/foo', 'POST')
    >>> req.request_url
    'http://localhost/foo'
    >>> req.make_url('show', id=1)
    '/show?id=1'