Fixes issue with metrics tab click handlers
  Click handlers were not getting attached to DOM elements in some cases on slow running machines.
  Added logic to attach handlers when elements are ready.

Added 2 buttons on metrics tab:
  Download Subsection Data for downloading to csv.
  Download Problem Data for downloading to csv.
Merge pull request #3584 from edx/dcadams/metrics_tab_download_csv

Metrics tab - fix click handlers and add download buttons
Allow creation of components on container page

This commit implements STUD-1490, allowing creation of components
on the container page. It also enables the delete and duplicate
buttons now that new content can be created that would benefit.
Revise drag and drop acceptance tests.
Remove vertical wrapper logic
fix for chrome flashing bug - removed webkit blur filter on prompt
Studio editor mixin to support reordering children.
Studio editor mixin to support reordering children.
Upgrade mock files
cleanup container styles - removed vert and vert-mod references
Fix the Bok Choy selector for Studio xblocks
Hide the buttons on child containers.
Address code review comments and fix child preview
Bok choy tests for add, duplicate, delete.
A couple of bug fixes

1. Render the xblock directly inline to get the video to work again. It didn't work to render the xblock to an element and then move it into the DOM.
2. Improve the logic so that the container knows how to refresh xblocks inside reorderable containers and inside unreorderable ones.
Fix bug when adding to a parent container
Remove obsolete vertical-element class
Add missing newlines at the end of files
Test that add and delete only add one thing.
Code review updates.