Add `If-None-Match` and `If-Modified-Since` headers as appropriate to the feed fetcher's requests. On well-configured web servers, this should short-circuit the request and reduce the amount of bandwidth and processing that is necessary.
A new table was added to the FeedDb to hold one etag per domain.
If-Modified-Since semantics are based on the creation date for the feed database, which should serve as a cutoff date for the earliest update we can have received.
This completes the changes for Issue #136.
This change adds `Accept-Encoding: gzip` to all outbound requests from the live crawler and feed fetcher, and the corresponding decoding logic for the compressed response data.
The change addresses issue #136, save for making the fetcher's requests conditional.
Introduced a method to decide whether to retain URI fragments in feed items based on their uniqueness. Enhanced FeedItem processing to conditionally strip fragments to maintain clean URLs where applicable.
Removed the redundant "RSS Feed Fetcher" suffix from the User-Agent header in the FeedFetcherService. This will help avoid making the feed fetcher trigger bot mitigation that accepts the regular UA-string.
Move the logic deciding which operation to perform into the actor, updating its state graph to incorporate a counter that runs a clean update once in a blue moon.
