Django 2.1 works fine - the only issue was that more passwords
have been added to the CommonPasswordValidator which caused some tests
to fail. I've removed that validator from the test settings.

Support for the old-style attributes was dropped in django-extra-views 0.11.

Also pin the version as the package does not use semantic versioning.

Fixes #2688.

We cannot rely on this being installed by django-phonenumber-field.
See https://github.com/django-oscar/django-oscar/issues/2681.

Fixes #2681.

Just released, that’s why

v2.0.0a was released recently which we are not yet compatible with.

The blocking dependency (Haystack) now supports Django 2.

Just assume django-haystack uses semver for now.

pytest-warnings is now part of pytest core. See https://docs.pytest.org/en/latest/changelog.html#id71

- Drop support for Django 1.9 (EOL)
- Drop support for Python 3.6 with Django 1.8 to 1.10

travis: Run py.test --cov=oscar instead of coverage run

This also updates the pytest dependencies