update RandomUserAgentMiddleware
test firebird with adbapi
scrapy contrib spider import
group spiders
[sqlmagic] some typo corrections, renamed SQLDBItem
modify Spiders for better durability against novice users.

Allows overriding parse() method in all Spiders, which use
another 'from_scraper' pre-parse hook instead, which in turn
calls parse().

As proposed in https://github.com/scrapy/scrapy/pull/732
This is not a "nice" change API-wise, but based on the amount
of issue reports it seems proven necessary useability-wise.
[spiders] Merge customized Spiders
[middleware] Merge cleaned RandomUserAgentMiddleware
[pipeline] Merge SQLMagicPipeline update. WIP