never_cache_patterns() is an old function of ours that applies

Django's @never_cache decorator to a list of URLs. It was built to

work like patterns(), which doesn't exist in modern versions of

Django, and assumed older URL semantics like the ability to associate

URLs with view lookup strings, which also doesn't exist anymore.
This updates the function to be more future-proof. It no longer requires

a prefix string as the first parameter, and in fact warns if a string

that is non-empty is provided, outright failing if provided on Django

1.10 or higher (which doesn't include prefix support).
Unit tests were added to test the function with and without prefix

strings, in a way that ensures things work properly on whatever version

of Django is being tested against.

Unit tests pass on Django 1.6, 1.9, 1.10, 1.11. Opting not to bother

with older versions at this stage.