Add the possibility to import answers of paper ballot

[Dynnammo]

As an admin, I would like to have the possibility not only to indicate how many paper ballots were filled but in fact import the real answers of the respondants.

As instance, let's say for the sake of simplicity, that we have a form containing a single option question, I would have a CSV file containing an id column and a column containing the answer to this question for each respondant.

This issue seems very hard to implement to me, but on the other side it could greetly benefit to the community, since a lot of cities/organisations use hybrid survey system (online and with persons in the street to increase the participation rate)