added seed data

app/controllers/posts_controller.rb

@@ -12,7 +12,7 @@ class PostsController < ApplicationController
   end
   
   def create
-    @post.user = current_user
+    @post.user ||= current_user
     if @post.save
       flash[:notice] = "Post was successfully created."
       redirect_to topic_path(@post.topic)

app/controllers/topics_controller.rb

@@ -7,7 +7,7 @@ class TopicsController < ApplicationController
   end
   
   def create
-    @topic.user = current_user
+    @topic.user ||= current_user
     
     if @topic.save
       flash[:notice] = "Topic was successfully created."