on AWS, automatically rotate backups

[drj11]

Backups on AWS are currently made automatically.

They appear as RDS- and EBS- snapshots.

Problem: Eventually an account will run into the limit of manual snapshots it can take.

Further Problem: Which means that CloudFormation will fail to delete a stack (it complains that it can't take a final snapshot).

Backups need to be identified and deleted according to some sort of reasonable retirement policy.

[hackdna]

Backups on AWS are not rotated after two weeks

[drj11]

• Tag EC2 instance so that scheduler rotates them out (tag EC2 instances for backups #1690)

• Document / enable launch of EBS Snapshot Scheduler (Add script to create EBS Snapshot Scheduler stack. #1693)

• remove EC2 snapshots from cron

• use RDS automatic backups for RDS

• remove RDS backups from cron

• CloudWatch events for tagging snapshots? (Let's not, for now)

[drj11]

Now #1693 and #1717 are merged this can be closed.