Numeric attribute values are exported as strings, not numbers

[lylejohnson]

When I have a DynamoDB item like this:

{
  "id": "7e7e9de9-cb80-4697-bbed-b112caa34050",
  "minValue": 0,
  "maxValue": 10000,
  "readingType": "Power",
  "units": "Watts"
}

where the types of minValue and maxValue are numbers (not strings), the exported version records them as strings:

{
  "id": "7e7e9de9-cb80-4697-bbed-b112caa34050",
  "minValue": "0",
  "maxValue": "10000",
  "readingType": "Power",
  "units": "Watts"
}

[sarjann]

Have a fix in #11