Delete document storage data when document is deleted

[ciur]

For each document there two folders where associated data (e.g. original document, OCR data per page) is stored:

• docs folder where document itself is stored
• sidecars where OCR data is stored

Both folders are under media root (settings.MEDIA_ROOT) and are of following format:

• <media root>/docs/<user id>/<doc id>
• <media root>/sidecars/<user id>/<doc id>

When deleting document - it is expected that both associated folders will be deleted :

• <media root>/docs/<user id>/<doc id>
• <media root>/sidecars/<user id>/<doc id>

However, current functionality (which is a bug) is that when document is deleted, its sidecar folder still remains.