Write event controller test suite

[shravanhariharan2]

Assertions we should test:

• Fetching events
  • GET / returns all lifetime events
  • GET /past returns only the events that have already ended
  • GET /future returns only the events that have not started
• Writing events
  • POST / creates an event if the attendance code provided is unused
  • POST / throws an error if a duplicate attendance code is provided
  • PUT / properly updates changed fields
• Event covers
  • POST /picture/:uuid updates the event's cover field
  • POST /picture/:uuid updates the S3 bucket on AWS with a properly named file
• Event feedback
  • Can be persisted and rewarded points when submitted for an event already attended
  • Is rejected on submission to an event not attended
  • Is rejected if sent multiple times to the same event
  • Is rejected if sent after 2 days of the event ending