Change position of csv reference

The reference may be used in other script.
It is safer to be included in init.inc.php.
Remove NewsRaw debug information
Change the crawl mechanism

1. Define Crawler_Common interface.

2. Remove crawl() methods from all crawlers.

3. NewsSourcesCfg will validate all class definition. Must implement
   Crawler_Common interface.

4. New Crawler::crawl method for crawling. Takes news id, crawler class
   and insert_limit as argument.