This gives the same upper limit to the live crawler and the big boy crawler, though the live crawler will reject items too large, and the big crawler will truncate at that point.
We should not wait until we've fetched robots.txt to decide whether we have any data to fetch! This makes the live crawler very slow and leads to unnecessary requests.
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.
Discovered feed URLs were given a double slash after their domain name in the DB. This will go away in the URL normalizer, so the URLs are still viable, but the commit fixes the issue regardless.
Feed discover is improved with by probing a few likely endpoints when no feed link tag is provided. To store the feed URLs, a sqlite database is added to each crawlset that stores a simple summary of the crawl job, including any feed URLs that have been discovered.
Solves issue #135
Updated the `documentBody` method to improve parsing retries and error handling. Refactored `ContentType` charset processing with cleaner logic, removing redundant handling for unsupported charsets. Also, updated the version of the `slop` library in dependency settings.
Also alter CrawledDocument to not require String parsing of the underlying byte[] data. This should reduce the number of large memory allocations quite significantly, hopefully reducing the GC churn a bit.
