[skeleton] drop whitelist_externals for flake8
whitelist_externals makes sense when used with sitepackages=true.
In this case it will always rely on $VIRTUAL_ENV/bin/flake8 so, the
whitelist_externals has no effect.
include *.py
include */*.py
recursive-include cubicweb_%(cubename)s *.py
recursive-include cubicweb_%(cubename)s/data *.gif *.png *.ico *.css *.js
recursive-include cubicweb_%(cubename)s/i18n *.po
recursive-include cubicweb_%(cubename)s/wdoc *
recursive-include test/data bootstrap_cubes *.py
include *.ini
recursive-include debian changelog compat control copyright rules
include cubicweb-%(cubename)s.spec