[#653] Support for RAW DATA export/import on non-monitoring groups

* When building the RAW DATA report, we need to query the Survey Group
  to know if is a _Monitoring_ group
* If is a monitoring group, we need to export 2 columns, `Identifier`
  and `Display Name`, otherwise we just keep with the old process
* When importing a RAW DATA report, we need to check if the spreadsheet
  contains the 2 extra columns
* We know the fragility of business logic based on indices, instead of
  the actual content of the column, but we're not adding more
  fragility to this process, it's fragile already ;)
Just to be pedantic, I would restructure this to instead only add if the `SurveyGroup` is successfully retrieved from the datastore. So that your whole call doesn't crash if this line malfunctions for whatever reason --> https://github.com/akvo/akvo-flow/pull/654/files#diff-4c2463ec87c4e22930feecc8d0f8a980L254