Treat restart_attempts as a string in govuk_containers::app
Treat restart_attempts as a string in govuk_containers::app

We are trying to validate $restart_attempts via regular expressions. In a
future parser world, regular expressions cannot be applied to a number so let's
stringify it before validating.

In the far-off Puppet 4+ world this validation can be replaced by Puppet data
types.

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