Extract user id from LTI values.
Extract user id from LTI values.

atomicjolt/OpenAssessments,BYU-Open-Analytics/BYUOpenAssessments,BYU-Open-Analytics/BYUOpenAssessments,BYU-Open-Analytics/BYUOpenAssessments,BYU-Open-Analytics/BYUOpenAssessments,atomicjolt/OpenAssessments,atomicjolt/OpenAssessments,atomicjolt/OpenAssessments,lumenlearning/OpenAssessments,lumenlearning/OpenAssessments,lumenlearning/OpenAssessments,lumenlearning/OpenAssessments