ActionFinish called after Action completion

The worker now calls ActionFinish on state to call home with the results of an Action.

The unit will not be set to an error state unless the API call to ActionFinish fails.  Any other errors generated by the Action will be encapsulated in the results message, which is sent back to state with the final state of the Action (complete or fail.)
it still shouldn't ever put the action into an error state, ever. We might return an action, lose the uniter, and restart it -- but that's fine. The critical thing is not to return errActionFailed.