Commit a831b5a9862f788ec5c474e0d8c64def87cb8659

DRC 2017-11-29T14:23:31

Travis: Work around xcode7.3 image bug Refer to travis-ci/travis-ci#8552. This was supposed to be fixed on November 15, then on November 28. Travis blew through both deadlines, so I have no confidence that the issue will be fixed as promised in a timely manner. Adding 'brew update' to .travis.yml slows the OS X build, but there is no choice at the moment.