update subscription in tutorial group.
Merge branch 'development' of github.com:Coursemology/coursemology.org into development

* 'development' of github.com:Coursemology/coursemology.org: (27 commits)
  removed precompiled assets from dev
  fix for creator nil error
  tmp fix for is_creator error
  redirect to update grade page for staff accessing submission
  precompiled assets
  precompiled assets
  disable submit button after click
  additional tab for training, publish for training and mission
  replace find with where for search user
  delete course only for course creator and superadmin
  better warning message when add student who is assigned tutor already
  regression fix: submissions sort by name
  python include code to be above
  display the latest 6 achievements in leader board
  achievement link and tooltip in leader board
  remove compiled assets from dev
  training review bug for coding question
  fix error message for training
  some fix for python eval
  precompiled assets
  ...