tox: logging
tox: logging

* `pytest-capturelog` is added as a dependency to capture logs on failed
testcases.
* `flake8` max-line-length parameter is added to avoid many lines long
log descriptions

Signed-off-by: Gergő Nagy <d3dcad219f7887bf0aa35b3eb99ea75d409b64fe@gmail.com>

ngergo/ratatoskr,hkrist/ratatoskr