blacken code and clean up test-env install, introduce pre-commit

[hairmare]

This PR reformats the code using black, configures isort & flake8 to match and adds pre-commit to the README as well as to the travis tests. I also took care of fixing or ignoring any issues found by flake8.

My apologies for the huge changeset, all of this does not touch/refactor any of the business logic or logic in setup.py (it touches how requirements are read from txt files in setup.py)... The changes to .travis.yml are kept as minimal as possible.

I plan on taking care of the werkzeug deprecation warnings in a future pull request and this prepares the repo to make it easy to do so. I'll also automate dependency bumping PRs once this is merged.

[codecov-io]

Codecov Report

Merging #16 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #16   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           1      1           
  Lines         481    481           
  Branches      109    109           
=====================================
  Hits          481    481

Impacted Files	Coverage Δ
klangbecken_api.py	100% <100%> (ø)	⬆️

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[smlz]

Hey Bicku

Finally things calmed down a bit, an I get to review your pull request.

This is really cool! Thanks a lot. Can you rebase the changes once more, with the current version of the project?

Also, I'd like to try black's --skip-string-normalization option, as this might significantly reduce the number of changes.

The deprecations are mostly gone by now, as authentication is now done with jwt-tokens instead of session cookies.

[smlz]

Try to move as much as possible to setup.cfg and reduce the number of dependencies to a minimum.

[smlz]

Can we add the --skip-string-normalization option here?

[hairmare]

I like the ' more than the " but I hate having to switch to what each project wants even more. If we skip string normalization we'll have a mix of " and ' pretty soon.

[codecov-commenter]

Codecov Report

Merging #16 into master will not change coverage.
The diff coverage is 72.46%.

@@           Coverage Diff           @@
##           master      #16   +/-   ##
=======================================
  Coverage   78.90%   78.90%           
=======================================
  Files           1        1           
  Lines         602      602           
  Branches      141      141           
=======================================
  Hits          475      475           
  Misses        110      110           
  Partials       17       17           

Impacted Files	Coverage Δ
klangbecken.py	78.90% <72.46%> (ø)

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[hairmare]

I addressed all the feedbacks except the one about --skip-string-normalization. I believe strongly that this needs to be standardized, in fact string normalization is one of the reasons I started this in the first place (after always finding myself using " and then changing it to ' to match with the remaining code). I would have been easier on everyone's eyes if we could have stuck with ' but this is mostly about delegating such mundane decisions to black, so " it is.

[spameier]

I addressed all the feedbacks except the one about --skip-string-normalization. I believe strongly that this needs to be standardized, in fact string normalization is one of the reasons I started this in the first place (after always finding myself using " and then changing it to ' to match with the remaining code). I would have been easier on everyone's eyes if we could have stuck with ' but this is mostly about delegating such mundane decisions to black, so " it is.

I agree. After all that's why we want to use black.