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
Clean up translated strings in registration page, dashboard, and track selection flow
Restore copy originally present on the registration page
Add middleware optionally to catch unenrolled students who fail has_access (TNL-286)
redirect users from about page to info page when there is a marketing site (TNL-286)
display banner on course info page if user is not enrolled (TNL-286)

write failing tests for info page banner
move to s3fs and handle one time url
only load tabs if user is enrolled in course (TNL-286)

add tests for static tabs
update number of queries in embargo test
Merge pull request #4898 from edx/danielli/recommender_pyfs

RecommenderXBlock with pyfs, better UX, and modification of logging
Hiding Insights link for non-staff users
Merge pull request #5188 from edx/insights-staff-only

Hiding Insights link for non-staff users
Added note about video URLs hidden by default
Merge pull request #5284 from edx/sylvia/docs/DOC-866

Sylvia/docs/doc 866
keep large answers from appearing (TNL-441)
Merge pull request #5248 from edx/renzo/cleanup-translated-strings

Clean up translated strings in registration page, dashboard, and track selection flow
Merge pull request #5281 from edx/adam/hide-tabs-if-not-enrolled-rebase-2

Deployed as hotfix
Change some text when in professional ed flow

ECOM-96
Merge pull request #5302 from edx/release

Release merge - post hotfix-2014-09-19-1
Updated help link and content of container page