devise_token_auth: Cannot use this gem alongside Devise

Hello. I cannot find a way to use this gem. I’m working on a Ionic app and I need Angular authentication. I don’t need Omniauth, mail and password login. Very simple.

I follow every step in the installation. I have a working Rails 4.1 app with Device installed and I’m using the beta 8 of Devise_token_auth.

I modify the migration file because I need only a couple of fields:

== 20150318160543 DeviseTokenAuthCreateUsers: migrating =======================
-- add_column(:users, :tokens, :text)
   -> 0.0014s
-- add_column(:users, :uid, :string, {:null=>false, :default=>""})
   -> 0.0439s
== 20150318160543 DeviseTokenAuthCreateUsers: migrated (0.0455s) ==============

In my user.rb I have

  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :confirmable, :validatable

  include DeviseTokenAuth::Concerns::User   

In my api base controller I have

module Api
  class BaseController < ApplicationController
    include DeviseTokenAuth::Concerns::SetUserByToken
    respond_to :json
  end
end

In my routes I have

namespace :api do
    namespace :v1 do
      mount_devise_token_auth_for 'User', at: 'auth', skip: [:omniauth_callbacks]
      resources :contents, only: [:index, :show] do
        get :hottest, on: :collection
      end
    end
  end

The result is

uninitialized constant ActionDispatch::Routing::Mapper::Scope

A brief question: how can I secure only update, post and delete method in my api?