[bug 825031] Change chunk size

This drops the chunk size from 50k to 20k. This will increase
the number of indexing chunks that get created and spread the load
across more workers. This will increase the load on ES (more things
being indexed at the same time), but probably shouldn't affect
mysql at all.

As a side note, since we set the chunk size at 50k, mysql got some
upgrades and shifts and is better now and we updated ES to 0.19.11
and it's doing better now, too.
[bug 779502] Fix ES_LIVE_INDEXING issues

* overrides the setting if you do ./manage.py esreindex figuring
  if you're running that on the command line you really mean it
  for realz srsly.
* puts a big warning note in the admin figuring it's hard to
  override it in the admin without fiddling with a lot of code, but
  a warning is helpful.
[Bug 823501] Make AAQ more like the default search

* Set a max age for questions.
* Use text_phrase queries as well as text queries.
[Bug 827645] Add FK columsn to questions.

* Locale FK for planned question localization.
* Product FK for possible future refactoring.
* Topic FK for possible future refactoring.
Alphabetizing rules for your Friday pleasure.