Add script for generating difference scores for activities

[#73976436][#73976902][#73976860]
Add progress reporting for scoring report
Allow searching only the browser-based Diy::Models

[#74565494]
Center the inner footer info (works with varying page widths)
Move activity hash functions to a library
Add activity side-by-side comparison

[#41062393]
Add navigation links for comparisons

[#41062393]
Hide private models in the models lists

Publication status isn't exposed in the authoring UI, so really this is
a way to manually hide certain models.

[#74799852]
Basic framework for browser-based views for sensor/prediction graphs
Change default top_level_container_name for itsisu to be "activity" (as it is on pro)

In config/initializers/01_load_config.rb on line 25 we try to set the class for the top-level container.( http://bit.ly/1jRCAK6 )

The default configuration for itsi sets the TOP_LEVEL_CONTAINER_NAME to "Unit" -- but ::Unit is not an actual class name, so I keep getting `uninitialized constant Unit`

On production this is set to "Activity".
[#74884614] Activate the grade_level, subject_area, and unit drop-downs for teachers

There was concern that this might cause non-exemplars to show up in the activity bins. They won't, because
the re-binning happens by overriding the grade-level and subject areas for the view if the activity is not an exemplar.

https://www.pivotaltracker.com/story/show/74884614
Add (very beta) support for lightweight prediction of lightweight sensor connector.

[#74566376] [#73974144]

https://www.pivotaltracker.com/story/show/74566376
https://www.pivotaltracker.com/story/show/73974144
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]