non-contact and non-response cases

[andreaskutka]

Issue:
Non-contact and non-response interviews are often included in the export files. They tend to be much shorter and follow a different path (e.g. consent == No -> Give details). They tend to be quite different to actually completed interviews. They may distort the scores and URS.

Solution:
Investigate thoroughly, once this type of survey is available.
Possibly add parameter to main.yaml to allow users to specify condition for interviews to be evaluated.