enabling docker remote API on Ubuntu 14.04 on GCE

docker_remote_api

* spin up a VM on GCE and
install docker (based on [these](https://docs.docker.com/installation/ubuntulinux/) instructions)

```bash
gcloud compute instances create dave --machine-type n1-standard-1 --image ubuntu-14-04
gcloud compute ssh dave
wget -qO- https://get.docker.com/ | sh
```

* to verify install is working

```bash
sudo docker run hello-world
```

* based on
[this](http://www.virtuallyghetto.com/2014/07/quick-tip-how-to-enable-docker-remote-api.html)
and
[this](http://blog.tutum.co/2013/11/23/remote-and-secure-use-of-docker-api-with-python-part-ii/)
enable docker's remote API

```bash
sudo sed -i -e 's/#DOCKER_OPTS="--dns 8.8.8.8 --dns 8.8.4.4"/DOCKER_OPTS="-H tcp:\/\/0.0.0.0:4243 -H unix:\/\/\/var\/run\/docker.sock"/g' /etc/default/docker
sudo service docker restart
```

* verify the remote API is enabled

```bash
curl -s http://127.0.0.1:4243/images/json | python -m json.tool
```