Add support of several scopes

Example
```ruby
class HomeController < ApplicationController
  acts_as_token_authentication_handler_for User, before_filter: false
  acts_as_token_authentication_handler_for AdminUser, before_filter: false

  before_filter :authenticate_user_from_token!, only: :destroy
  before_filter :authenticate_admin_user_from_token!, only: :destroy_all

  def index
    # ... Accessible for unauthenticated users ...
  end

  def destroy
    # ... Only for authenticated users...
  end

  def destroy_all
    # ... Only for authenticated admins...
  end
end
```