Feature channel reward deleted

[JayJay1989]

This pull request adds the forgotten channel reward deleted event.

{
    "type": "custom-reward-deleted",
    "data": {
        "timestamp": "2019-12-26T23:30:50.054696516Z",
        "deleted_reward": {
            "id": "37bb2890-177f-4a5e-bb44-d6e777a8340e",
            "channel_id": "63937599",
            "title": "Does Nothing",
            "prompt": "This does nothing",
            "cost": 250,
            "is_user_input_required": true,
            "is_sub_only": false,
            "image": null,
            "default_image": {
                "url_1x": "https://static-cdn.jtvnw.net/custom-reward-images/default-1.png",
                "url_2x": "https://static-cdn.jtvnw.net/custom-reward-images/default-2.png",
                "url_4x": "https://static-cdn.jtvnw.net/custom-reward-images/default-4.png"
            },
            "background_color": "#6E0574",
            "is_enabled": false,
            "is_paused": false,
            "is_in_stock": true,
            "max_per_stream": {
                "is_enabled": false,
                "max_per_stream": 0
            },
            "should_redemptions_skip_request_queue": true
        }
    }
}

[swiftyspiffy]

Confirmed it's been tested.