WIP. Adding hint create page.
Added /add_hint/:level_source_id to insert hint messages.
Merged from origin/master.
Added a link on each of the stats page for adding hint.
Added a show page that shows all the hints.
Minor changes in cleaning code up.
Changing _code_group partial to have has instead of array as input for code clarification.
Bug fix for link on add and show hint.
Merge from master.
Merge pull request #252 from nanan9177/feedback_collect

Feedback collect