Create default configuration

[lindseyanderson]

CloudFormation templates take the opinionated stance of defining the BackupsEnabled option, in reference to setting the "Backup" tag, to "False" by default. This binary setting leads to the value being set to "True" without verifying the current configuration set within ebs_snapper. The onboarding team sets specific Backup tags, such as 'Daily30,' to reference the retention and frequency which doesn't match this default option.

To avoid any issues in the future due to not verifying a configuration, we propose deploying a default configuration set for the following with each deployment of ebs_snapper:

{"snapshot": {"minimum": 1, "frequency": "1 day", "retention": "14 days"}, "match": {"tag:Backup": "True"}}

[mlattanzi]

It would be good to have this default set so that if an explicit backup policy isn't specified but 'True' is we are in fact getting snapshots.
This would also help prevent us needing to remember to add this default on every build.