add the gitlab-runner binary so that the build will work on Kubernetes

Dockerfile.www-gitlab-com

@@ -5,6 +5,9 @@ ENV PACKAGES="git-core pandoc texlive-latex-recommended texlive-xetex texlive-fo
 ADD / /
 RUN /scripts/install-www-gitlab-com
+ADD https://gitlab-ci-multi-runner-downloads.s3.amazonaws.com/latest/binaries/gitlab-ci-multi-runner-linux-amd64 /usr/bin/gitlab-runner-helper
+RUN chmod +x /usr/bin/gitlab-runner-helper
+
 # Set UTF-8 http://jaredmarkell.com/docker-and-locales/
 # Must be set after install-essentials is run
 ENV LANG en_US.UTF-8