Fix for issue #1205 - Populated data source with label/values to avoid the need to parse student id out of label
Issue #956 - Tracking of record_event field for inclusing in subquery(in progress)
#956 - generate and attach subquery to base query
Fixed issue that caused the user search to fail #956
Removes attendance app, which was never used.

It has no views, isn't in our INSTALLED_APPS, and the .pyc files didn't even
exist so it was never imported.  Trying to import the models file errors due to
a broken import.  Seems like it's time for it to go into retirement.
Removes esp.utils.file_cache

Not sure what this was, but I've never heard of it, and it's never imported.
Doesn't look very useful.
Removes what appears to be the old HSSP lottery.

The main lottery script now does this, and does it much better.
Removes some old scheduling sanity checks.

I don't think this has been used since ~2010, and we now have a much better
scheduling checks page.
Removes some old class changes scripts.
Remove some unused memcache utils.

I have no idea why we ever wanted to run multiple memcache instances, but I
don't think we do anymore.
Removes the file users/tests-defunct.py, last really touched in 2008.

Need I say more?  Also removes some utils only used by those tests.
Removes esp.lib.TOC.

I don't really know what it was, but we don't seem to use it.
Removes esp.lib from INSTALLED_APPS.

Not sure how it wasn't erroring since it doesn't have a models.py or
views.py...
Removes esp.middleware.psycomiddleware.
Removes esp.middleware.scopecachemiddleware.
Removes esp.shortterm.

I don't know what most of these things are, but they were short term, right?
And I think it's time for the venerable crazy_excel_thing to move somewhere
more usefully-named and findable.
Removes esp.middleware.esp_session.
Removes esp.db.prepared

Some old SQL stuff, probably died with the datatree.
Removes esp.db.idebug.

Appears to be some debugging thing, I don't think we've used it in recent
memory.
Removes DB prepared models that aren't used.