Saved a Panamax template arangodb_nginx.pmx

This panamax template starts up arangodb and nginx in two docker containers.  The arangodb server can be accessed in the nginx server via the arangodb alias in /etc/hosts

The demo works best if you mount a directory and clone `https://github.com/rseymour/arango_demo.git` into it as `arango_demo`.  This is explained in the docs.

Re-opening the pull request to get rid of a bunch of unnecessary commits.  I will tweet about this at http://twitter.com/rseymour