Move timelines API from statuses to its own controller, add a check for

resources that require a user context vs those that don't (such as public timeline)

/api/v1/statuses/public   -> /api/v1/timelines/public
/api/v1/statuses/home     -> /api/v1/timelines/home
/api/v1/statuses/mentions -> /api/v1/timelines/mentions
/api/v1/statuses/tag/:tag -> /api/v1/timelines/tag/:tag

app/controllers/api/v1/follows_controller.rb

@@ -1,5 +1,7 @@
 class Api::V1::FollowsController < ApiController
   before_action -> { doorkeeper_authorize! :follow }
+  before_action :require_user!
+
   respond_to    :json
 
   def create