Mistral/Blueprints/repeater

As per various discussion on changed the specification.

The DSL snippet: repeat_task: action: action_name repeat: iterations : iterations delay : delay_in_sec break-on : yaql_expr on-finish: on_finish_task_ref : yaql_expr on-error: on_error_task_ref

1. This is a mechanism to repeat a specific action as per the repeat specification. 2. 'repeat' is an optional property of the Task. 3. on-finish/on-error/on-success i.e. and subsequent tasks are only scheduled after iterations are complete.

The original design and parts of that discussion will be used to implement a mechanism to repeat a set of tasks. However, this will require calling out to other workflows and requires a separate blueprint. (TODO add link.)

Etherpad https://etherpad.openstack.org/p/std_repeat