cloudflare: fix purging of cached urls.

* Switch CloudflareService from HttpartyCache to Danbooru::Http.

* Purge cached urls from Cloudflare when a post is replaced and the md5
  doesn't change. This happens when a corrupted image is replaced or
  thumbnails are regenerated. Before we purged urls when a post was
  expunged, which was unneeded because those urls can expire naturally.
  It was also wrong because the subdomains were hardcoded, the urls used
  http:// instead of https://, and we didn't account for tagged urls.

app/logical/upload_service/replacer.rb

@@ -123,6 +123,8 @@ class UploadService
         CurrentUser.as(User.system) do
           post.comments.create!(body: comment_replacement_message(post, replacement), do_not_bump_post: true)
         end
+      else
+        purge_cached_urls(post)
       end
 
       replacement.save!
@@ -131,6 +133,18 @@ class UploadService
       post.update_iqdb_async
     end
 
+    def purge_cached_urls(post)
+      urls = [
+        post.preview_file_url,
+        post.large_file_url,
+        post.file_url,
+        post.tagged_large_file_url,
+        post.tagged_file_url
+      ]
+
+      CloudflareService.new.purge_cache(urls)
+    end
+
     def rescale_notes(post)
       x_scale = post.image_width.to_f  / post.image_width_was.to_f
       y_scale = post.image_height.to_f / post.image_height_was.to_f