put autograder into a separate module.
include AutoGrader in CodingQuestionGrading.
add normal grader for mcq question, change coding question to only upate grade after students have finished all questions.
remove auto_grader from training_submission.
Merge branch 'dev/multi_grader' into development

* dev/multi_grader:
  remove auto_grader from training_submission.
  add normal grader for mcq question, change coding question to only upate grade after students have finished all questions.
  include AutoGrader in CodingQuestionGrading.
  put autograder into a separate module.