Below issues resolved in PR:

1. "/pa help like" and "/pa help dislike" do not work
2. Percentage of likes not included in "/pa stats" output for course
3. "/pa like" adds a vote for the last course completed, but there's no validation for extra args, e.g. course name, which could be confusing: e.g.
   "/pa like blue_course" would return "You liked red_course" or "You have already voted for red_course" (if red_course was the last completed course).
4. resultset closed exception from getVotePercent method