1.0.0

Breaking changes of the linter usage.

The linter now is a Django management command.
It should be used with a python manage.py lintmigrations followed by the usual options.
Additionally, the linter now needs to be added the to the INSTALLED_APPS in your Django settings.

• The linter is now much faster: we don't setup django once for each migration
• The linter is now more robust: we rely on Django internals to discover migrations
• Clean up of the testing setup: it is cleaner, less brittle and we have more confidence that it works
• Added support for Django 2.2
• Dropped support for Python 3.4

Fixed bugs:

• Made the cache database-dependent. Between multiple databases, some migrations would be considered correct while they are not on the used DB.
• Adding an erroneous migration to the ignore list on the second run would get the migration content from the cache and not ignore it.