add an example to paas-incubator to show the use of sidekiq with ruby and the redis backing service

[pauldougan]

Teams using ruby typically want to use sidekiq with their application and a redis backing service. It would be helpful to have a simple example in the incubator that we can point developers at to help them understand the pattern in the context of Cloud Foundry

[pauldougan]

DFE have a standard boilerplate ruby app https://github.com/DFE-Digital/govuk-rails-boilerplate that defines a base project to bootstrap development. They are using sidekiq and redis so we may be able to collaborate around this