Wrote combine arrays question.
ArrayQuestions: corrected increment array.
GradeArrayQuestions: added incrementArray.
ArrayQuestions: fixed getArrayMin and getArrayMax return type.
GradeArrayQuestions: wrote grader for getArrayMin and getArrayMax.
ArrayQuestions: should use UnansweredQuestionException.
GradeArrayQuestions: wrote grader for sumArray.
GradeArrayQuestions: added extra test for getArrayMax and getArrayMin.