User orders channel

// subscribe request
{
    "command": "subscribe",
    "identifier": "{\"channel\":\"UserOrdersChannel\",\"market\":\"ETH-BTC\"}"
}

// confirmation
{
    "type": "confirm_subscription",
    "identifier": "{\"channel\":\"UserOrdersChannel\",\"market\":\"ETH-BTC\"}"
}

// response structure
// pending
{
    "identifier": "{\"channel\":\"UserOrdersChannel\",\"market\":\"ETH-BTC\"}",
    "message": {
        "order": {
            "id": "1d475f9d-c883-4daf-8370-be43124960e4",
            "market": "ETH-BTC",
            "price": "0.0761",
            "size": "0.001",
            "size_filled": "0.0",
            "fee": "0",
            "funds": "0.0000761",
            "status": "pending",
            "order_type": "buy",
            "post_only": false,
            "operation_type": "limit_order",
            "created_at": "2018-03-19T17:33:43.300588Z"
        }
    }
}

// fulfilled
{
    "identifier": "{\"channel\":\"UserOrdersChannel\",\"market\":\"ETH-BTC\"}",
    "message": {
        "order": {
            "id": "1d475f9d-c883-4daf-8370-be43124960e4",
            "market": "ETH-BTC",
            "price": "0.0761",
            "size": "0.001",
            "size_filled": "0.001",
            "fee": "0.00000019025",
            "funds": "0.0000761",
            "status": "fulfilled",
            "order_type": "buy",
            "post_only": false,
            "operation_type": "limit_order",
            "created_at": "2018-03-19T17:33:43.300588Z"
        }
    }
}