Add clean-tox make target to remove testing artifacts
Add clean-tox make target to remove testing artifacts

dajose/cookiecutter,hackebrot/cookiecutter,luzfcb/cookiecutter,pjbull/cookiecutter,dajose/cookiecutter,audreyr/cookiecutter,luzfcb/cookiecutter,audreyr/cookiecutter,hackebrot/cookiecutter,stevepiercy/cookiecutter,willingc/cookiecutter,terryjbates/cookiecutter,willingc/cookiecutter,michaeljoseph/cookiecutter,stevepiercy/cookiecutter,pjbull/cookiecutter,michaeljoseph/cookiecutter,terryjbates/cookiecutter