feature: support this metric: Daily Conversion Date

[9ssi7]

The metric namedDaily Conversion Date % should be developed.

Example Request

GET /metrics?id=conversion&dimensions=date&aggregate=distinct

Example Response

{
  "metric": "conversion",
  "dimensions": ["date"],
  "aggregation": "distinct",
  "data": {
    "2020-10-09": [
      {
        "sessions": 100,
        "purchases": 10,
        "value": "10.00"
      }
    ],
    "2020-10-10": [
      {
        "sessions": 1000,
        "purchases": 250,
        "value": "25.00"
      }
    ]
  }
}

[9ssi7]

fixed at #20