[hotfix] fix bug for importing HLP courses

[michellemtchai]

• issue raised in #175
• Cause:
  • the dates attributes in HLP courses in the CHASS JSON has a different format than other course
  • HLP: month day - month day
  • other courses: month day, year to month day, year
  • this created an error with parsing the dates and creating a sessions model.
  • without a Session model, the Position model, which was dependent on it, was not created