Adds rmdir to permitted sudo list for www-data user
Initial modifications for dual-worker plan

Uses static 20K transfer size instead of variable
Adds variable/file for parsed chunks
One thread will download 20K parts then update the IndexedDB or File System API counter
to indicate that the decrypter has data available
Adds basic function outline for worker-based method
Adds basic status updates from workers

Implements the 'get avail data' portion for inter-worker communication
to allow synchronization between download worker and decrypt worker
Adds function to update available chunks

Message posted to worker in addition to a global array maintained
when quantity requested