Add an app definition for 'release'
Add an app definition for 'release'

Before the 'release' app can exist in our infrastructure we need one of
these app classes within Puppet. This sets the relevant database and
nginx/unicorn config up so that we have the barebones of what we need.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet