Urgent hotfix patch.

v1.2.0 (which has been pulled from PyPI) had an issue where importing
InstantCoverageAPI would cause a bunch of additional failing tests to be
added to your test suite.

Type annotations and more versions tested.

There should be no functional changes in this release. The changes worth
noting are:

- mypy-compatible type annotations on everything.
- Newer versions of Python and Django covered in the tests, up to 3.11
  and 4.2 respectively.

Support Django 2.0.

I'm shipping now because I now have a 2.0 project I'm using this against
for real.

We no longer test against Python 3.3, either, but only because of a
change in one of our dependencies. You should still be good on 3.3 if
you're already using it.

The Snow Leopard of Instant Coverage releases.

Nothing really significant changed here. For more information on why this is
1.0, see issue #10.

For the record, though, we're now testing against Django 1.10, so I guess you
could consider that support.

Support Django 1.9.

As always, most of the changes here were to fix the tests rather than actual
functionality; I already confirmed stuff works on a real project, so you should
be okay, but upgrading is always recommended.

Don't use HEAD to test external URLs.

This is mostly so that I can get rid of my attempt_to_get_external_url
overrides in projects I maintain.

Django 1.8 support and some minor client abstraction.

Use HEAD when testing external URLs.

Django 1.7 support.

ExternalLinks Abstraction

If you want to specify a custom user agent or reattempt on connection
errors, it's now a lot easier; just override attempt_to_get_external_url.