🔖 Thalia Website v1.16.2

Errors resolved

• Fix pizzas uniqueness (!872 (merged)) pizzas
• Fix/registrations form entry missing (!868 (merged)) registrations
• Crash on confirming non-existing registration entry (!867 (merged)) registrations

New functionality

• Access Sentry access permission and API call to provide necessary auth info (!866 (merged)) members

Technical changes

• Change Raven logging level to INFO (!885 (merged))
• Hotfix: Update Django to 2.0.8 (!880 (merged)) security
• Replace Slack reporting by Sentry reporting (!875 (merged))
• Fix punctuation discrepancies in the translations (!871 (merged))
• Make starting year a dropdown in registration form (!869 (merged)) registrations