* 🔧 Add pre-commit config
Similar to graphene and graphene-sqlalchemy
* ⬆ Bump black
* 👷 Lint on CI
* ⬆ Bump flake8-black
* 🔧 Keep excluding migrations
* ⬆ Bump flake8
* 🔧 Remove black and flake8 from tox config
* ⬆ Update pre-commit versions
* Upgrade syntax to python 3.7+
* Format with pre-commit
dedent docs/schema.py to allow formatting
* Fix tests on python 3.7
* Update travis and tox
* Use xenial distribution
* Don't install coveralls twice
* Add black and flake8 tox commands
* Remove Python 3.5 test for Django master
* Fix indent
* Ignore migrations
* Remove black for now
* Run black formatting (#668)
* Run black format
* Update makefile
* Add black to travis build