Updated topics.py to correctly create the nodecache from latest KA API.

Updated nodecache and topics.py.

Updated Video navigation for new keys.
Bug fix: Khan Academy had removed related videos from exercises data.

Now retrieved via separate API call.
Updated topics.py to correctly download all topic data.

Also now generate knowledgemap data, and download icons.

Missing icons are replaced by the default icon.
Script to pull latest Khan-Exercises repository.

KA Lite platform is not currently compatible with latest exercises.
Remove knowledgemap utils - this functionality is now within topics.py
First pass at converting scatter view to d3.

Original functionality replicated - now with user name hover, as well as click summary tooltip.

TODO:
* Replicate for timeline view.
* As all data has been retrieved through API, only refresh graph on axes change.
* Prettification.
Timeline view now switched over to D3.

Line plots highlight when appropriate legend is mouseovered.

TODO:
*Reduce y-axis options, and test all x-axis options.
*Integrate new activity reports into timeline.
*Use Raphael to give IE backwards compatibility.
Clean up of cruft.

TODO:
See last commit.
now generate user usage logs.
add version not just to fields, but also to models.
this only works when we increment the version :)
missed this critical change for getting syncing to work; not having this breaks... everything\!
Merge branch 'user_logs_syncing' of github.com:bcipolli/ka-lite into user_logs_syncing
Merge remote-tracking branch 'upstream/develop' into user_logs_syncing
Merge branch 'user_logs_syncing' of github.com:bcipolli/ka-lite into user_logs_syncing
get cron settings from settings.py/local_settings.py; make sure to use same executable to run cron as cronserver was run.
resolve sync warnings
Merge remote-tracking branch 'jamalex/require_admin_account_at_install' into configurable_cron
initial checkin to launch cron async from the django server
Merge remote-tracking branch 'upstream/develop' into IDOC_coach_reports_jQuery

Conflicts:
	kalite/templates/coachreports/timeline_view.html