Fix mint hub.docker.com builds (#7908)

Dockerfile.mint

@@ -0,0 +1,23 @@
+FROM ubuntu:16.04
+
+ENV DEBIAN_FRONTEND noninteractive
+
+ENV LANG C.UTF-8
+
+ENV GOROOT /usr/local/go
+
+ENV GOPATH /usr/local
+
+ENV PATH $GOPATH/bin:$GOROOT/bin:$PATH
+
+ENV MINT_ROOT_DIR /mint
+
+COPY mint /mint
+
+RUN apt-get --yes update && apt-get --yes upgrade && \
+    apt-get --yes --quiet install wget jq curl git dnsmasq && \
+    cd /mint && /mint/release.sh
+
+WORKDIR /mint
+
+ENTRYPOINT ["/mint/entrypoint.sh"]