fixed small markup issue
renamed class for correctness
shifted css-class for correctness
Fix html editor buttons
Add superscript and subscript
Enable iframes for youtube embed
update attributes in coding_question create
set default mem time attempt limit to coding questions
show hints of private test cases in missions
Add basic insert youtube video function
refine code as hound suggests
Improve youtube video uploader
Merge pull request #227 from weiqingtoh/bug/mission-attempt-alignment

Bug/mission attempt alignment
use a function to set hints for both mission and training
refine code
Allow youtube video to display on forum posts
Add javascript style checking to hound🐶
remove empty answers
Merge pull request #229 from wangqiang1208/bugfixing/mission-hints-for-private-test

show hints of private test cases in missions
Merge pull request #231 from jsyeo/jsyeo-enable-js

Add javascript style checking to hound🐶