[#4477] Added a paid field to track when a FixedBudget is spent

db/migrate/017_add_paid_to_fixed_budgets.rb

@@ -0,0 +1,10 @@
+class AddPaidToFixedBudgets < ActiveRecord::Migration
+  def self.up
+    add_column :fixed_budgets, :paid, :boolean
+    add_index :fixed_budgets, :paid
+  end
+
+  def self.down
+    remove_column :fixed_budgets, :paid
+  end
+end