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.
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.
To avoid hammering the same invalid URLs for up to two months, URLs that fail to fetch correctly are on a dice roll added to a bad URLs table, that prevents further attempts at fetching them.
Since some of the export tasks have been memory hungry, sometimes killing the executor-services, they've been moved to a separate process that can be given a larger Xmx.
While doing this, the ProcessMainClass was given utilities for the boilerplate surrounding receiving mq requests and responding to them, some effort was also put toward making the process boot process a bit more uniform. It's still a bit heterogeneous between different processes, but a bit less so for now.
This is done by applying a large constant offset to the ordinals for the live crawled documents. The chosen value still permits upto 100k documents to be fetched for a single domain with the live crawler, which is ridiculously large.
