Make email adresses unique

db/migrate/20161208092632_unique_emails_for_persons_and_users.rb

+class UniqueEmailsForPersonsAndUsers < ActiveRecord::Migration[5.0]
+  def change
+    add_index :users, [:email], unique: true
+    add_index :people, [:email], unique: true
+  end
+end

db/schema.rb

 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20161208091531) do
+ActiveRecord::Schema.define(version: 20161208092632) do
 
   create_table "activities", force: :cascade do |t|
     t.string   "public_name"
     t.boolean  "is_admin"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.index ["email"], name: "index_people_on_email", unique: true
   end
 
   create_table "users", force: :cascade do |t|
     t.integer  "person_id"
     t.datetime "created_at",           null: false
     t.datetime "updated_at",           null: false
+    t.index ["email"], name: "index_users_on_email", unique: true
     t.index ["person_id"], name: "index_users_on_person_id"
   end