* 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.
Bug: Notes weren't rescaled when the 'final_source' field was given
during replacement.
The cause was that the notes were rescaled after the source was saved,
but saving the source clobbered `image_{width,height}_before_last_save`
inside `rescale_notes`.
Regressed in b0c2ddba.
