Bump secret key length to 32

app/controllers/profiles/two_factor_auths_controller.rb

 class Profiles::TwoFactorAuthsController < Profiles::ApplicationController
   def new
     unless current_user.otp_secret
-      current_user.otp_secret = User.generate_otp_secret(16)
+      current_user.otp_secret = User.generate_otp_secret(32)
       current_user.save!
     end
 

spec/controllers/profiles/two_factor_auths_controller_spec.rb

@@ -12,7 +12,7 @@ describe Profiles::TwoFactorAuthsController do
     let(:user) { create(:user) }
 
     it 'generates otp_secret for user' do
-      expect(User).to receive(:generate_otp_secret).with(16).and_return('secret').once
+      expect(User).to receive(:generate_otp_secret).with(32).and_return('secret').once
 
       get :new
       get :new # Second hit shouldn't re-generate it

spec/factories.rb

@@ -31,7 +31,7 @@ FactoryGirl.define do
     trait :two_factor do
       before(:create) do |user|
         user.otp_required_for_login = true
-        user.otp_secret = User.generate_otp_secret(16)
+        user.otp_secret = User.generate_otp_secret(32)
       end
     end