Update problem_test unit tests
Update problem_test unit tests

- converted to create_simple_user_request
- added instance_number to the test problem instances to match current
  api
- added a sid when problems are inserted (valid for a single server
  setup)

picoCTF/picoCTF-web,picoCTF/picoCTF-web,cganas/picoCTF-web,picoCTF/picoCTF-web,cganas/picoCTF-web,cganas/picoCTF-web,picoCTF/picoCTF-web,cganas/picoCTF-web