Company: add 2 more questions

Hi @wichert ,

OSHA requests to have 2 more questions in the company survey.

My first attempt to achieve this was to put everything into https://github.com/euphorie/osha.oira/tree/extra_questions_survey to not pollute Euphorie with this. I got pretty far, but things got hairy when I tried to actually save the data. Some magic seems to be happening in client.model that I was not able to reproduce, even though I overrode model.Company in osha.oira and (tried) to make sure it was used in the session instead of the one from Euphorie. 

Adding everything directly in Euphorie on the other hand seems pretty straight-forward (== this branch).
Is the company survey even used by TNO? If not, then adding this would seem possible (and I would welcome a critical view from you on my changes in this case).

If TNO does use the company survey and does not want those 2 extra questions, we obviously need a different solution. What would you recommend in that case?
The 2 general options I see are
* we manage to make this work in osha.oira, maybe with your help?
* we keep a seperate branch of Euphorie for OSHA (not something I would look forward to).

Cheers,
Wolfgang