Release Checklist

Update CHANGELOG
Verify that all CI tests pass for current master
Tag the release, and push to Github
Wait for tag CI to complete
Download assets from https://snapshots.mitmproxy.org
Create release notice on Github
Upload wheel to pypi (twine upload wheelname)
Update docker-releases repo
- Create a new branch based of master for major versions.
- Add a commit that pins dependencies like so: 3d6a9989fd.
  - The requirements can be obtained by creating a fresh venv, pip-installing the new wheel in there, and then running pip freeze. * virtualenv -ppython3.5 venv && source venv/bin/activate && pip install mitmproxy && pip freeze
Update latest tag on https://hub.docker.com/r/mitmproxy/mitmproxy/~/settings/automated-builds/
Bump the version in https://github.com/mitmproxy/mitmproxy/blob/master/mitmproxy/version.py and update https://github.com/mitmproxy/mitmproxy/blob/master/mitmproxy/io_compat.py in the next commit