Use pretty colored Fabric output
Add Fabric task for formatting user-data

This makes it easier to grab the user-data for an EC2 image. You can
run:

    $ fab test user_data | pbcopy

to copy it to your OSX clipboard.
Fix a few issues in bootstrapping files

We need the Docker config in both /root/ and /home/ubuntu/ as:

- The user-data process runs as root and needs it in /root/.
- Any manual Docker interactions runs as the ubuntu user and so needs it
  in /home/ubuntu/.
Adjust requirements to have django-extensions in the base

It's needed everywhere as it's in INSTALLED_APPS.
Reference the correct base image in release Dockerfile
Remove uWSGI stats socket (for now)

It was causing a permissions error. Will revisit later.
Remove old reference to DJANGO_CONF
Correct how Docker builds are tagged in fabfile
Tweak Docker startup script
Webserver bootstrap script now (almost) works

Can't quite get the docker pull to work - seems to struggle to find a
~/.dockercfg file to use. Never mind - will bypass this by pushing
Docker deployment into a script called by cron.
Update Docker containers using deploy script

This commit removes the attempt to "docker pull" from the user data
script and moves all docker container starting into a deploy script
which is pulled from S3 into /opt/deploy.sh and run every 5 minutes by
cron.

Notes:

- We need to store the S3 bucket URL in /etc/ so it can be looked up by
  the deploy script.

- This makes the webserver bootstrap script much simpler as we just need
  to install nginx and put the deploy script in place.

- The deploy script compares the running Docker image to that on S3 and
  starts a new container if they differ. It doesn't do anything clever
  like running two containers side by side (yet). In fact, it doesn't
  stop the old container but it does update the nginx file to point to
  the new container.
Ensure uWSGI reads env vars from /var/www/.env