[MIN] Use ctx manager to get user instead of session
[REF]actoring ETicket class and getModEticket method
[IMP] Use new function from util for date formatting
[FTR] Add CheckIn to registrants management
[FIX] Timezone issue with checkInDate
[FIX] Update checkInDate on check in ajax call
[IMP] Change QRCode to JSON string
[IMP] Allow OAuth over the Authorization header
[FIX] Test if registrant exists before access
[IMP] Extend QR Code to include registrant id
[FTR] Add HTTP API for registrant info retrieval
[FTR] Add checkin to HTTP API
[FIX] Attachment adding
[FIX] Use new interface for check
[FTR] Add event list to HTTP API
[FIX] Unlink creator when deleting conference
[FTR] Add registrants list to HTTP API
[MIN] Replace PIL with Pillow
[FIX] Check if e-ticket is enabled in HTTP API
[FTR] Add check in/uncheck in from registrant eticket tab