Deprecated zesty dockerfile

The apt-get update used in the ubuntu zesty dockerfile triggers a Failed to fetch 404 Not Found. It is due to the fact normal intermediate Ubuntu releases such as zesty are supported for 9 months, whereas LTS (Long Term Support) releases are supported for 5 years. Once support is up for the version of Ubuntu you are using, the repository is moved to another server and will no longer be available on the standard http://archive.ubuntu.com/ubuntu/dist/ location.

To fix this, run sed -i -e 's/archive.ubuntu.com\|security.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list before the apt-get update