users: give all users unlimited favorites.

Let all users have unlimited favorites. Formerly the limit was 10k
favorites for regular members, 20k for Gold, and unlimited for Platinum.

Limiting favorites doesn't make sense since upvotes are unlimited.

app/models/favorite.rb

@@ -29,9 +29,7 @@ class Favorite < ApplicationRecord
     Favorite.transaction do
       User.where(id: user.id).select("id").lock("FOR UPDATE").first
 
-      if user.favorite_count >= user.favorite_limit
-        raise Error, "You can only keep up to #{user.favorite_limit} favorites. Upgrade your account to save more."
-      elsif Favorite.for_user(user.id).where(:user_id => user.id, :post_id => post.id).exists?
+      if Favorite.for_user(user.id).where(:user_id => user.id, :post_id => post.id).exists?
         raise Error, "You have already favorited this post"
       end