Broker ECS operations should be made idemptotent

[spiegela]

Currently, the broker operations can not be retried easily from Cloud Foundry. This means that if a create/delete/update operation completes from the broker to ECS, but there is a disruption before Cloud Foundry sees that result, the broker is left in an inconsistent state with Cloud Foundry.

In order to correct this issue, each operation should be made idempotent, meaning it can be executed any number of times without error.

The following operations will need to be updated:

• Create Bucket
• Delete Bucket
• Change Bucket Plan
• Create Namespace
• Delete Namespace
• Change Namespace Plan
• Create Remote Bucket
• Delete Remote Bucket
• Note: Changing a remote bucket plan is not supported