question rating

-question_rating table created
-unit-v , unit_m updated (added new functions)
-added rating_m
-base view of question rating is done
-still need to check for user log on to vote the rating
must log in to rate a question
question rating update

-deleted rating_m and switch the codes to questions_m
unit rating updated

- unit_rating table created
- modified the codes in units_m for rating table to unit_rating table
deleted rating table
unit_rating on unit-v changed

- unit rating show as X% positive rating, Y% negative rating
added "%" for unit rating on negative rating (it was missing)
deleted the debug lines
unit rating acts the same as question rating

- After a user rated on an unit / question once, the up/down buttons
will do nothing (so user can't change their mind once they voted)
fixed problems on view for question+answer+rating

-added skilljoy(1).sql for testing
deleted some test lines

- ready for merge
before merge
delete debug line
Merge pull request #16 from m-mmoocs/question_rating

Question rating