Cosmetic: Renamed ``views_tests`` filename to match the styling.
Define models for the footer ``Sponsors``.

https://github.com/madewithbytes/us_ignite/issues/165

The sponsors is an ordered list of Companies with
a link to their website.
Add template tag to render footer ``Sponsors``.

https://github.com/madewithbytes/us_ignite/issues/165

The tag passes an ordered ``object_list`` of ``Sponsors``
to the given template. Usage::

    {% render_sponsors "sections/sponsor_list.html" %}

Where the second argument is a template name or variable.
Add admin section to manage the ``Sponsors``.

https://github.com/madewithbytes/us_ignite/issues/165

Admin section manages lightly the sponsors.
Add help text describing the image field functionality.
Bugfix: Make sure the image is rendered in the template.

https://github.com/madewithbytes/us_ignite/issues/165
Render ``Sponsors``in the base template.

https://github.com/madewithbytes/us_ignite/issues/165

The sponsors are meant to appear on every page of of the
site.