Successful jobs should include IDs of whatever was created.#3000

Right now when scheduling posts via the API, we get the job id of the async task. When the task is successful we only get a “successful” and are left with querying all scheduled posts to see where the post we just sent landed. Having the success response include a list of IDs of things that were created (post ids for schedule posts, or media id for uploading media) would save API queries and make identifying scheduled posts / uploaded media really easy.