No need for the docker cli in the test runner

We now use the docker REST api exclusively.

Author: tanuck

test/integration/runner/Dockerfile

@@ -5,14 +5,6 @@ ENV DOCKER_VERSION 1.12.0
 ENV DOCKER_SHA256 3dd07f65ea4a7b4c8829f311ab0213bca9ac551b5b24706f3e79a97e22097f8b
 
 RUN apt-get update -y && apt-get install -y build-essential git curl
-RUN set -x \
-	&& curl -fSL "https://${DOCKER_BUCKET}/builds/Linux/x86_64/docker-$DOCKER_VERSION.tgz" -o docker.tgz \
-	&& echo "${DOCKER_SHA256} *docker.tgz" | sha256sum -c - \
-	&& tar -xzvf docker.tgz \
-	&& mv docker/* /usr/local/bin/ \
-	&& rmdir docker \
-	&& rm docker.tgz \
-	&& docker -v
 
 RUN curl -sL https://deb.nodesource.com/setup_6.x | bash - && apt-get install -y nodejs python-software-properties python