Remove v0 version namespacing for API

spec/controllers/api/playlists_controller_spec.rb

@@ -1,6 +1,6 @@
 require 'spec_helper'
 
-describe Api::V0::PlaylistsController do
+describe Api::PlaylistsController do
   before do
     controller.current_user = Factory.create(:user)
   end

spec/controllers/api/sessions_controller_spec.rb

@@ -1,6 +1,6 @@
 require 'spec_helper'
 
-describe Api::V0::SessionsController do
+describe Api::SessionsController do
   describe 'POST create' do
     let(:user) { Factory.create(:user) }