Suppress Rule List Errors Regarding Status Fetches

[dubee]

When calling wsk rule list, an error can occur if a listed rule is deleted by the time the command fetches the status of that rule. We should just omit the rule from the list if the rule no longer exists (status code 404).

[mdeuser]

or update the backend to include the status value with the other rule definition data being returned as part of the wsk rule list backend api invocation. this would avoid multiple backend calls from the cli.

[rabbah]

The status of the rule isn't part of the rule doc in the backend - it would be another db hit to fill this out.