show all the explanations if answer is correct
change implementation to show only for MRQ questions
check if results[index] == test[expected]
change results parsed to test_result_table in do_coding partial
Merge pull request #226 from wangqiang1208/bugfixing/auto-grader-results-compare

fix auto grader "test cases all green" bug
Merge pull request #222 from wangqiang1208/feature/training-correct-answer-explanation

show all answer explanation for MRQ questions