a store is now responsible to store the downloaded content only.
where as the queue (local, remote) tracks now the URLs.
Merge branch 'master' of github.com:cederigo/crawl.js

* 'master' of github.com:cederigo/crawl.js:
  updated docs in main files
  Update README.md
  updated

Conflicts:
	lib/dispatcher.js
	lib/fetcher.js
	lib/queue.js
	lib/store.js
	tools/importer.js