New Checkpoint model. Update factories. Model specs.

db/migrate/20170620132731_create_budget_investment_checkpoints.rb

@@ -0,0 +1,11 @@
+class CreateBudgetInvestmentCheckpoints < ActiveRecord::Migration
+  def change
+    create_table :budget_investment_checkpoints do |t|
+      t.integer :investment_id
+      t.string   "title", limit: 80
+      t.text     "description"
+
+      t.timestamps null: false
+    end
+  end
+end