default result sorting to quiz submission descending

completes #85

db/migrate/20161204220527_add_completed_at.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+class AddCompletedAt < ActiveRecord::Migration[5.0]
+  def change
+    add_column :candidates, :completed_at, :datetime, after: :completed
+
+    Candidate.reset_column_information
+    Candidate.where(completed: true).each do |candidate|
+      candidate.completed_at = candidate.updated_at
+      candidate.save
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20161120175737) do
+ActiveRecord::Schema.define(version: 20161204220527) do
 
   create_table "answers", force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=utf8" do |t|
     t.integer  "candidate_id"
@@ -32,6 +32,7 @@ ActiveRecord::Schema.define(version: 20161120175737) do
     t.string   "experience"
     t.integer  "recruiter_id"
     t.boolean  "completed"
+    t.datetime "completed_at"
     t.boolean  "reminded"
     t.datetime "created_at",                null: false
     t.datetime "updated_at",                null: false
@@ -77,11 +78,11 @@ ActiveRecord::Schema.define(version: 20161120175737) do
   create_table "reviewer_votes", force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=utf8" do |t|
     t.integer  "candidate_id"
     t.integer  "user_id"
-    t.integer  "vote",          default: 0,     null: false
-    t.integer  "veto",          default: 0,     null: false
+    t.integer  "vote",          default: 0, null: false
+    t.integer  "veto",          default: 0, null: false
     t.datetime "last_reminded"
-    t.datetime "created_at",                    null: false
-    t.datetime "updated_at",                    null: false
+    t.datetime "created_at",                null: false
+    t.datetime "updated_at",                null: false
     t.index ["candidate_id", "user_id"], name: "index_reviewer_votes_on_candidate_id_and_user_id", unique: true, using: :btree
   end