Fix up data coordination between lightweight prediction and lightweight sensor.

It now will queue events properly, so both graphs don't need to be
loaded before using the prediction graph.
Listen for 'clear' events so the prediction clear button works correctly
Re-sync prediction data to sensor graph periodically and whenever the sensor graph is reset
Optimize rake task resetting all lightweight flags
Add cap task for resetting lightweight status of activities
publication_status should always be a string, not symbol

[#75520084]
Activities are now private by default, since draft was removed as a valid status at some point
Fix a duplication bug where data collectors weren't finalized by the time observers were running.

They were trying to determine if an activity could run lightweight, but
failing since the data collectors weren't finished being set up.

Also, this should speed up creation/duplication because the observers
should only run once now, instead of 3-4+ times.

[#75520084]
Identify browser-based sensor graphs with section names
Use a different placeholder image for sensor graphs

[#76140204]
Add more info to the compare view (id, author, created/modified times)

[#74977286][#75462522]
Explicitly require diff/comparison. Fixes a bug on staging.
Enable viewing students' labbook albums in the reports for browser-based activities

[#29965231]