Travis: allow failures on PyPy
Travis: allow failures on PyPy

Until https://github.com/travis-ci/travis-ci/issues/5027 is resolved the
builds on PyPy are going to fail because the Apache.org servers use
HTTPS with SNI.

django-haystack/pysolr,toastdriven/pysolr,django-haystack/pysolr,toastdriven/pysolr