Roles and permission related features

[Daandelange]

Currently, only "authorised user roles" can view stats in the panel and there is still some polishing to do.
Plus introducing user-permissions would be useful.

• Double-check if all restricted zones are fully restricted.
• Permission suggestions :
  • Be tracked (to disable tracking)
  • View stats
  • View configuration
  • Generate stats (or only locally ? or when dev=true ?)
  • Export/backup database