The additional extract_messages call in the pep8 tox environment
generates a lot of meaningless output, that then makes it difficult
to spot actual failures and warnings. This patch makes the Django
command respect the verbosity setting and call the setup.py command
with a quiet flag if low verbosity is requested, considerably decreasing
the amount of useless output. It then sets that verbosity to low in the
corresponding tox environment.
Change-Id: I2976250a23e800fbb582726299670b57199b58a7
c3b6fc761e