Add subscription model and link it to RFC

test/factories/subscriptions.rb

@@ -0,0 +1,7 @@
+FactoryGirl.define do
+  factory :subscription do
+    user nil
+    request_for_comments nil
+    type ""
+  end
+end

test/models/subscription_test.rb

@@ -0,0 +1,7 @@
+require 'test_helper'
+
+class SubscriptionTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end