Add utilities to generate request doubles.
Add utilities to generate request doubles.

The new ``get_request`` function is a helper used to generate
request doubles the first argument is the ``method``, an
optional user can be attached to the request.

us-ignite/us_ignite,us-ignite/us_ignite,us-ignite/us_ignite,us-ignite/us_ignite,us-ignite/us_ignite