[#4420] Add frequency to deliverables for Retainers.

db/migrate/011_add_frequency_to_deliverables.rb

@@ -0,0 +1,9 @@
+class AddFrequencyToDeliverables < ActiveRecord::Migration
+  def self.up
+    add_column :deliverables, :frequency, :string
+  end
+
+  def self.down
+    remove_column :deliverables, :frequency
+  end
+end