adds order by score to debates

db/migrate/20150903155146_add_cached_votes_score_to_debate.rb

@@ -0,0 +1,7 @@
+class AddCachedVotesScoreToDebate < ActiveRecord::Migration
+  def change
+    add_column :debates, :cached_votes_score, :integer, default: 0
+
+    add_index :debates, :cached_votes_score
+  end
+end