dd Docker binaries to instance image of GitLab QA

[ci skip]

qa/Dockerfile

@@ -8,6 +8,13 @@ ENV DEBIAN_FRONTEND noninteractive
 RUN sed -i "s/httpredir.debian.org/ftp.us.debian.org/" /etc/apt/sources.list
 RUN apt-get update && apt-get install -y wget git unzip xvfb
 
+##
+# Install Docker
+#
+RUN wget -q https://download.docker.com/linux/static/stable/x86_64/docker-17.09.0-ce.tgz && \
+    tar -zxf docker-17.09.0-ce.tgz && mv docker/docker /usr/local/bin/docker && \
+    rm docker-17.09.0-ce.tgz
+
 ##
 # Install Google Chrome version with headless support
 #