added user authentication

app/models/user.rb

+class User < ApplicationRecord
+  # Include default devise modules. Others available are:
+  # :confirmable, :lockable, :timeoutable and :omniauthable
+  devise :database_authenticatable, :registerable,
+         :recoverable, :rememberable, :trackable, :validatable
+end

config/routes.rb

 Rails.application.routes.draw do
+  devise_for :users
   # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
 end

db/migrate/20160718134705_devise_create_users.rb

+class DeviseCreateUsers < ActiveRecord::Migration[5.0]
+  def change
+    create_table :users do |t|
+      ## Database authenticatable
+      t.string :email,              null: false, default: ""
+      t.string :encrypted_password, null: false, default: ""
+
+      ## Recoverable
+      t.string   :reset_password_token
+      t.datetime :reset_password_sent_at
+
+      ## Rememberable
+      t.datetime :remember_created_at
+
+      ## Trackable
+      t.integer  :sign_in_count, default: 0, null: false
+      t.datetime :current_sign_in_at
+      t.datetime :last_sign_in_at
+      t.string   :current_sign_in_ip
+      t.string   :last_sign_in_ip
+
+      ## Confirmable
+      # t.string   :confirmation_token
+      # t.datetime :confirmed_at
+      # t.datetime :confirmation_sent_at
+      # t.string   :unconfirmed_email # Only if using reconfirmable
+
+      ## Lockable
+      # t.integer  :failed_attempts, default: 0, null: false # Only if lock strategy is :failed_attempts
+      # t.string   :unlock_token # Only if unlock strategy is :email or :both
+      # t.datetime :locked_at
+
+
+      t.timestamps null: false
+    end
+
+    add_index :users, :email,                unique: true
+    add_index :users, :reset_password_token, unique: true
+    # add_index :users, :confirmation_token,   unique: true
+    # add_index :users, :unlock_token,         unique: true
+  end
+end

db/schema.rb

@@ -10,7 +10,24 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20160718134153) do
+ActiveRecord::Schema.define(version: 20160718134705) do
+
+  create_table "users", force: :cascade do |t|
+    t.string   "email",                  default: "", null: false
+    t.string   "encrypted_password",     default: "", null: false
+    t.string   "reset_password_token"
+    t.datetime "reset_password_sent_at"
+    t.datetime "remember_created_at"
+    t.integer  "sign_in_count",          default: 0,  null: false
+    t.datetime "current_sign_in_at"
+    t.datetime "last_sign_in_at"
+    t.string   "current_sign_in_ip"
+    t.string   "last_sign_in_ip"
+    t.datetime "created_at",                          null: false
+    t.datetime "updated_at",                          null: false
+    t.index ["email"], name: "index_users_on_email", unique: true
+    t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
+  end
 
   create_table "votes", force: :cascade do |t|
     t.integer  "user_id"

test/fixtures/users.yml

+# Read about fixtures at http://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
+
+# This model initially had no columns defined. If you add columns to the
+# model remove the '{}' from the fixture names and add the columns immediately
+# below each fixture, per the syntax in the comments below
+#
+one: {}
+# column: value
+#
+two: {}
+# column: value

test/models/user_test.rb

+require 'test_helper'
+
+class UserTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end