Improve CSV Export

[etudor]

When exporting results, all fields that are not string appear as [object Object] in the CSV file.

It would be nice to have the path to the value as a column in CSV.
For example let's assume we have

{
  "title": "iPad",
  "price": {
    "amount": 300,
    "currency": "GBP"
  }
} 

then the CSV file will be:

title,price.amount,price.currency
iPad,300,GBP

Current CSV export will produce:

title,price
iPad,[object Object]