title: Routing Error : uninitialized constant when split controller routes into namespaced route
body: <p>I have routes like this below. Is it possible if I have routes like this ?</p>
  
  <pre><code>#config/routes
  resources :subscribers, only: [:index, :show]
  
  namespace :admin do
      resources :subscribers, only: [:new, :edit, :update, :create, :destroy]
  end
  </code></pre>
  
  <p>I have tried to run <em>rake routes</em> and the result is</p>
  
  <pre><code>admin_subscribers     POST /admin/subscribers(.:format)     admin/subscribers#create
  new_admin_subscriber  GET  /admin/subscribers/new(.:format) admin/subscribers#new
  edit_admin_subscriber GET  /admin/subscribers/:id/edit(.:format) admin/subscribers#edit
  admin_subscriber      PUT  /admin/subscribers/:id(.:format) admin/subscribers#update
                        DELETE /admin/subscribers/:id(.:format)    admin/subscribers#destroy
  subscribers           GET    /subscribers(.:format)         subscribers#index
  subscriber            GET    /subscribers/:id(.:format)     subscribers#show
  </code></pre>
  
  <p>the result was appropriate with my expectation, but when i run my RSpec i got errors</p>
  
  <pre><code>Routing Error
  uninitialized constant Admin::SubscribersController
  Try running rake routes for more information on available routes.
  </code></pre>
  
  <p>I added this code below in my Rspec Helper too</p>
  
  <pre><code>#spec/spec_helper.rb
  
  Spork.each_run do
  ###
  
     if /spork/i =~ $0 || RSpec.configuration.drb?
       ActiveSupport::Dependencies.clear
     end
  
  ###
  
  end
  </code></pre>
  
  <p>But, if I fire my browser to htt**://l*alhost:3000/admin/subscribers/new, everything is fine. 
  Am I missing something ?</p>