Merge branch 'atomaka/bugfix/moren1' into 'master'

Fix some more n+1 stuff

Some quick fixes. Only noteworthy thing is nested includes can be done as so:

```
Comments.all.includes(post: :subcreddit)
```

See merge request !25

app/controllers/subcreddits_controller.rb

@@ -10,7 +10,7 @@ class SubcredditsController < ApplicationController
   end
 
   def show
-    @posts = @subcreddit.posts
+    @posts = @subcreddit.posts.includes(:user)
 
     authorize @subcreddit
   end

app/controllers/users_controller.rb

@@ -2,7 +2,7 @@
 class UsersController < ApplicationController
   def show
     @user = User.friendly.find(params[:id])
-    @comments = @user.comments.includes(:post)
+    @comments = @user.comments.includes(post: :subcreddit)
   end
 
   def new