add cdn hosted flag to posts

app/models/amazon_backup.rb

@@ -21,7 +21,8 @@ class AmazonBackup < ActiveRecord::Base
       region: "us-east-1",
       credentials: credentials
     })
-    client = Aws::S3::Client.new
+    logger = Logger.new(STDOUT)
+    client = Aws::S3::Client.new(logger: logger)
     bucket = Danbooru.config.aws_s3_bucket_name
 
     Post.where("id > ?", last_id).limit(1000).order("id").each do |post|

app/models/post.rb

@@ -105,7 +105,11 @@ class Post < ActiveRecord::Base
     end
 
     def file_url
-      "/data/#{seo_tag_string}#{file_path_prefix}#{md5}.#{file_ext}"
+      if cdn_hosted?
+        Danbooru.config.danbooru_s3_base_url + "/#{file_path_prefix}#{md5}.#{file_ext}"
+      else
+        "/data/#{seo_tag_string}#{file_path_prefix}#{md5}.#{file_ext}"
+      end
     end
 
     def large_file_url
@@ -1709,6 +1713,7 @@ class Post < ActiveRecord::Base
 
   BOOLEAN_ATTRIBUTES = %w(
     has_embedded_notes
+    cdn_hosted
   )
   has_bit_flags BOOLEAN_ATTRIBUTES