instance configuration can't cope with symbol values 

example:

    Iqvoc.available_languages = [:en, :de]
    Iqvoc::Concept.pref_labeling_languages = [:en]
    Iqvoc::Concept.further_labeling_class_names = {
        'Labeling::SKOS::AltLabel' => [:en, :de]
    }

While this works initially, attempts to change any configuration values via the web interface will fail:
"Errors occurred while updating configuration: unsupported value: available_languages (unsupported type: Symbol)"