add option to create item

[sfunkhouser]

Adds the ability to use the https://invoice.zoho.com/api/v3/items endpoint to create a new item

[sfunkhouser]

Looks good. Have you tested?

And thanks for the contribution!

Yep, works on something I was doing with a simple:

    req := invoice.CreateItemRequest{
        Name:  "A unique name",
        Rate: "10",
        Unit: "Hourly",
    }

    id, err := zc.createZohoItemID(req)
    if err != nil {
        return "", err
    }

[schmorrison]

Tagged v1.0.5