Shuffle feature for multiple choice questions

Add more granular pageview tracking, update Segment.io snippet

Features by Jeff Ericson and Nick Parlante squashed
down to one commit.

-shuffle of choices within a choicegroup (Nick)
-answer-pool subsetting within a choicegroup (Jeff)
-masking of choice names within a choicegroup, (Nick)
 used by shuffle and answer-pool
-targeted-feedback within a multiplechoiceresponse (Jeff)
-delay-between-submissions capa feature (Jeff)

Added analytics event logging to PDF book viewer

Release Apr 14, 2014

Conflicts:
	cms/templates/widgets/source-edit.html

Fix unit test.

This makes the metrics tab "bars" clickable.

Update translations (autogenerated message)

Disable HD control when HD is not available [BLD-937]

Rc/2014 04 14

player.getAvailableQualityLevels returns a non-empty array, it will eventually display, if HD qualities are available (highres, hd1080, hd720). [BLD-937]

Introducing JSHint.

fix change name view by replacing the request.user simple lazy object wi...

Update acceptance tests to use real duration of YouTube video.

Fix course urls in enrollment emails (LMS-2217)

  Clicking on any of the bars displays a list of students for that
  particular action (either opened the subsection or attempted the
  problem).
  Students are listed for the sub-sections.
  Students, grade and percent are listed for the problems.
  The on-screen list displays only the first 250 students with
  an overflow message if there are more students than that.
  The csv download lists all students.

DOC-252, add section on interpreting answer distribution

Release

Fix for fuzzy prompt on Studio Pages

Upgrade JSDraw.

Video: Refactor speed control.

LMS-2479

Nimisha/container duplicate delete