global: pytest rewrite

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
tasks: removed files are ignored

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
tasks: wip component is ignored for push

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
docs: updating the doc.

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
global: flake8 and python2 fixes

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>