Rollback Django Debug Toolbar from 1.0.1 to 0.9.4

Due to issues with require.js and the latest version of the toolbar.
Also included a note in the requirements file explaining the situation, and what
needs to happen before this can be upgrade properly.
Add label information to problem types
Add new screen shots
Add label information to Appendix E
Added drafts for speed_change_video and seek_video event types
Changed scrollbar to playback bar per Carlos
Added change log for the Data Formats part of the guide
Clarified historical effect of the speed_change_video event type
Very minor tweaks.
Update information about rescoring submissions
Quick edits
i18n open_ended_rubric (ORA-314)

update strings
Add new container page that can display nested xblocks

This is the changes for STUD-1244, which introduces the ability for Studio to display
arbitrarily nested xblocks. In this change, a new container page is introduced which can
display nested xblocks. In particular, the xblock type of 'vertical' is special cased
to be shown inline as a collapsible section. The unit page is mostly unchanged, except
that container xblock's are shown as a link to their container page, rather than being
shown inline.