Add Linting/Code Formatting

[seanlaw]

@louisabraham Would it be useful to add flake8 and black for linting and code formatting, respectively?

Perhaps, this is something we can do later once Travis CI is in place

[louisabraham]

Yes, the current code is formatted in black. I have never used Travis for linting or code formatting.

[seanlaw]

Neither have I but I can only assume that it must be possible. I currently perform linting/code formatting checks on Azure Pipelines before accepting any public PR. While it is possible to automate it, I haven't gotten to that level yet. Usually, the check is sufficient to highlight red flags

[louisabraham]

It is now done on travis. I also added code coverage reports as a bonus