Provide more translations for the new countee page

[dnsos]

The page new_counting_countee_path is crucial to the application. It is used when interviewing encountered people and since these people may not all speak German or English, we need to add other locales for this page (other pages probably don't need more locales since volunteers may be familiar with either German or English).

Which locales should be added?

TBD

How to approach this feature?

Probably we have to add new columns to the models that need translation (Gender, AgeGroup, ?). We then need to allow other locales in the Rails config and make sure that other pages without translations don't break. We also need to add the new locales to the locale dropdown in the header area.