Spawn worker as default.
Raise error when worker is not running.
Give crawl url.
Use crawl url.
Don't give crawl_url when worker is not running.
Reload entries when worker is not running.
Option for disable worker.
Missing set running as false.
Classify worker.
Test for worker that doesn't running.
Changelog for worker thread by default.
Merge pull request #46 from Kjwon15/worker-thread

Spawn worker as default.