adds video spec

spec/factories.rb

@@ -507,6 +507,12 @@ FactoryGirl.define do
     sequence(:description) { |n| "Question description #{n}" }
   end
 
+  factory :poll_answer_video, class: 'Poll::Question::Answer::Video' do
+    association :answer, factory: :poll_question_answer
+    title "Sample video title"
+    url "http://sample-video-url.org"
+  end
+
   factory :poll_booth, class: 'Poll::Booth' do
     sequence(:name) { |n| "Booth #{n}" }
     sequence(:location) { |n| "Street #{n}" }