aligns document verification with census API

app/models/verification/management/document.rb

@@ -32,7 +32,7 @@ class Verification::Management::Document
   end
 
   def under_sixteen?(response)
-    16.years.ago < string_to_date(response.date_of_birth)
+    16.years.ago < response.date_of_birth
   end
 
   def verified?

lib/active_model/dates.rb

@@ -13,9 +13,4 @@ module ActiveModel::Dates
     attrs.except("#{field}(1i)", "#{field}(2i)", "#{field}(3i)")
   end
 
-  def string_to_date(value)
-    day, month, year = value.split("-")
-    Date.new(year.to_i, month.to_i, day.to_i)
-  end
-
 end