Create a new Message

POST https://mutation.prepr.io/v5/messages

{
    "id": "caf5c136-f62a-4e65-b5b4-078d2bt73651",
    "created_on": "2017-03-08T15:46:41+0000",
    "changed_on": null,
    "label": "AppMessage",
    "nickname": null,
    "body": "Hello world",
    "audio_url": null,
    "video_url": null,
    "audio_source_url": null,
    "video_source_url": null,
    "photo_url": "2017/03/13/app_b054cef86d85b7031335ee1b8f53601f.jpg",
    "sent": {
        "id": 38007134,
        "created_on": 1478526999,
        "changed_on": 1488473951,
        "structure": 50,
        "structure_label": "Person",
        "preposition": "mr",
        "initials": "JJ",
        "firstname": "Jan",
        "prefix_lastname": "",
        "lastname": "Janssen",
        "nickname": null
    }
}