Initial port timed exams
more porting timed exams
cherry-picked unload message code change
Merge branch 'master' of https://github.com/Stanford-Online/class2go
More Khan stuff to remove
Merge branch 'master' of https://github.com/Stanford-Online/class2go
alert to warn users if they are using IE that their work won't save
Merge pull request #2073 from Stanford-Online/jbau-interstitial

Jbau interstitial
Change confirmation message which didn't make sense for autograded timed exam
Disable save work btn and take "too many attempts" msg out of {% elif %}

Doing these because presently, if there's time remaining
after an exam submission, re-opening the exam shows a disabled submit
button but not disabled save answer button, and doesn't say anything
about why submissions are disabled.
Merge pull request #2099 from Stanford-Online/jbau-interstitial

Change confirmation message which didn't make sense for autograded timed...
Merge pull request #2096 from Stanford-Online/dca_new_working2

Fix content disposition (#1879)
Merge pull request #2100 from Stanford-Online/jbau-interstitial

Disable save work btn and take "too many attempts" msg out of {% elif %}
Small change in	handling of slideIndices key to	account for float conversion

Older manifests	like Solar had slideIndices keys like 0.0, which
breaks the slide section function because parseFloat converts it
to 0, and then slideIndices[0] would not be found.  This fixes it
by using the actual key to dereference.
Merge pull request #2101 from Stanford-Online/jbau-slide-selection-fix

Small change in	handling of slideIndices key to account for float conversion
Merge pull request #2093 from Stanford-Online/giulio-ie-alert-1988

Added alert to warn users using IE that quizzes and assignments won't save or submit
Merge pull request #2090 from Stanford-Online/sef-more-de-khan

More Khan stuff to remove
Issue #2104

1. Current quizzes summary report:
  - order the quizzes alphabetically
  - remove in-video quizzes from the list

2. New report - student scores
  - same content as Student Scores report under Reports menu
  - must filter by username for MOOCs
  - can run for whole class if internal
Merge branch 'master' of http://github.com/Stanford-Online/class2go into dca_new_working2