Finalise packaging metadata.

[carltongibson]

• Licence file and trove classifier
• Other classifiers
• requires and python_requires.
• ...

[carltongibson]

e.g.

install_requires = [
    "Django",
]

[carltongibson]

But also...

    ...
    "Sphinx",
    ...

#15 Makes both Django and Sphinx hard dependencies. It would be good to make that not so... — If you want to use the view, sure you need Django; if you're building the docs, sure you need Sphinx; but you shouldn't need Sphinx just to use the view (and vice versa).