Rename description to chapter_description
Add course introduction to training_app_courses
Add introduction to ember
Style the course intro page
Fix classroom page selector
Merge branch 'dynamic-course-intro'

* dynamic-course-intro:
  Fix classroom page selector
  Style the course intro page
  Add introduction to ember
  Add course introduction to training_app_courses
  Rename description to chapter_description
Permit all course params on admin
Style instructors
Fix title on course page