Direct messages column (#4514)

* Added a timeline for Direct statuses
* Lists all Direct statuses you've sent and received
* Displayed in Getting Started
* Streaming server support for direct TL

* Changes to match other timelines in 2.0

config/routes.rb

@@ -229,6 +229,7 @@ Rails.application.routes.draw do
       end
 
       namespace :timelines do
+        resource :direct, only: :show, controller: :direct
         resource :home, only: :show, controller: :home
         resource :public, only: :show, controller: :public
         resources :tag, only: :show