secure-cookies: Allow to use secure HTTPS cookies (Django setting)

Cf https://docs.djangoproject.com/en/1.4/ref/settings/#std:setting-SESSION_COOKIE_SECURE
Make code more robust to bad input (for case where DB was populated with string None)
Draft of mobile FAQ for students
Draft of mobile FAQ
Draft of mobile FAQ
Revisions to mobile FAQ for students
Update app post name and course list
Add 'we'll be adding more courses' text
Tweak demo course description
Add line breaks
Don't put all of xmodule_js as src (changes coverage metrics).
set overflow to scroll so that user can see full content with increased font size
TNL-256
Update final text strings & readthedoc URL

TNL-401
Use ddt for shib tests
Remove test cleanups

Since `ddt` should make them unnecessary
Address PR review comments
image files with different extensions should generate thumbnails with distinct names (TNL-532)
Make student profile CSV download a background task, add cohort column
Fix cached definition change detection
LMS-11485
Remove extraneous dollar sign in template