Added order's dispatcher's info into the order payload

We have added more details for the dispatcher user in the order's response payload.

The dispatcher object comes with the following properties:

        ...
        "dispatcher": 
        {
            "is_active": true,
            "created_at": "2019-11-15T10:33:29.112+0000",
            "changed_at": "2019-11-15T10:33:29.112+0000",
            "guid": "4f797316-63a8-432a-a4ef-2986b8occ89d",
            "username": "ZH058gvXGpyHwHQFbxLH",
            "email": "johndoe@mail.com",
            "first_name": "John",
            "last_name": "Doe"
        },
        ...