Travis: Disallow failures of Django 1.11
Travis: Disallow failures of Django 1.11

jleclanche/dj-stripe,jameshiew/dj-stripe,jleclanche/dj-stripe,dj-stripe/dj-stripe,kavdev/dj-stripe,jameshiew/dj-stripe,pydanny/dj-stripe,kavdev/dj-stripe,pydanny/dj-stripe,dj-stripe/dj-stripe