Updated default config to use valid task types

The new task types are actually used by Flamenco Server.

flamenco-worker.cfg

 [flamenco-worker]
 manager_url = http://localhost:8083/
-task_types = sleep blender-render ffmpeg filemanage
+task_types = sleep blender-render file-management
 task_update_queue_db = flamenco-worker.db
 
 may_i_run_interval_seconds = 5