add server side to tracking plan (transport url defined in json)

[VinceCabs]

Tracking plan now:

{
    "test_cases": {
        "home_engie": {
            "events": [
                {
                    "dp": "A"
                },
                {
                    "dp": "B"
                },
                {
                    "dp": "C"
                }
            ]
        }
    }
}

Target:

{
    "test_cases": {
        "home_engie": {
            "transport_url": "tracking.example.com",
            "events": [
                {
                    "dp": "A"
                },
                {
                    "dp": "B"
                },
                {
                    "dp": "C"
                }
            ]
        }
    }
}