Add default 0 value for Poll Recount amounts

db/migrate/20171002191347_add_default_to_recount_amounts.rb

@@ -0,0 +1,7 @@
+class AddDefaultToRecountAmounts < ActiveRecord::Migration
+  def change
+    change_column_default :poll_recounts, :white_amount, 0
+    change_column_default :poll_recounts, :null_amount, 0
+    change_column_default :poll_recounts, :total_amount, 0
+  end
+end