Merge branch 'development' into sso

# Conflicts:
#	core/src/main/java/nl/tudelft/ewi/auta/core/Core.java
#	core/src/main/java/nl/tudelft/ewi/auta/core/controller/AssignmentController.java
#	core/src/main/java/nl/tudelft/ewi/auta/core/controller/CourseController.java
#	core/src/main/java/nl/tudelft/ewi/auta/core/controller/SubmissionController.java
#	core/src/main/java/nl/tudelft/ewi/auta/core/response/ErrorCode.java
#	core/src/test/java/nl/tudelft/ewi/auta/core/controller/CourseControllerTest.java