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.
Remove loading mark even task fails.
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.
Remove unused import.
Organise imports.
Python 3.4 support
Make app.py be compatible with Python 3.x

Note: Tkinter has been renamed to tkinter in Python 3.
Use USE_WORKER config instead of calling spawn_worker() manually

Because spawn_worker() was removed, therefore app.py didn't work.
Merge pull request #47 from Kroisse/fix

Fix app.py
[ci skip]
Workaround libearth 0.3.0 incompatibility