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
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
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
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
Merge pull request #5473 from edx/dan-f/background-student-profiles-add-cohort

Make student profile CSV download a background task, add cohort column
Merge pull request #5475 from edx/andya/cohort-doc-fixes

Update final text strings & readthedoc URL
Fix error when doing non-ASCII forum search

Fixes TNL-160
Add cohort information to forum search events
Remove dead code
Add events for cohort modifications

This includes cohort creation/deletion and membership changes.