TestDataBuilder does not autopopulate property values unless the type name starts with an uppercase letter.

This gets auto populated:

```
    "date": {
      "type": "Date",
      "required": true
    },
```

whist this doesn't:

```
    "date": {
      "type": "date",
      "required": true
    },
```

Both are valid schema definitions that mean the same thing to Loopback. They should both cause the property value to be auto populated
