def flatten_keys(hash, prev_key=nil, &block)
      hash.each_pair do |key, value|
        curr_key = [prev_key, key].compact.join('.')
        if value.is_a?(Hash)
          flatten_keys(value, curr_key, &block)
        else
          yield curr_key, value
        end
      end
    end
def flatten_keys(hash, prev_key=nil, &block)
      hash.each_pair do |key, value|
        curr_key = [prev_key, key].compact.join('.')
        if value.is_a?(Hash)
          flatten_keys(value, curr_key, &block)
        else
          yield curr_key, value
        end
      end
    end
convert translations hash to flat keys
 i.e. from { :de => {:new => neue, :old => alt} } to [ ['de.new', 'neue'], ['de.old', 'alte'] ]
 and yields a flat key and the value to the block