implemented collection ExerciseProgress in order to keep user's best performance for an exercise
Merge branch 'dev' of https://github.com/INSA-4IF-SpecIFic/elif into dev

Conflicts:
	src/job.py
Merge branch 'dev' of https://github.com/INSA-4IF-SpecIFic/elif into dev

Conflicts:
	src/model/exercise.py