Release 1.1.0

• reserve only one extra task per celery worker
• save uploaded photos/scans to the database and retrieve one-by-one in the celery workflow
• optimize celery workflow by merging a long task chain into one task
• avoid running code multiple times on one file for each color during marking detection
• enable beat to run backup cleanup (a built-in periodic task which will delete the tasks results)
• improve database connection handling:
  • implement two clients: one for celery and one for flask
  • one database connection per celery worker
  • and avoid errors due to cached db connection