Reindexing doesn't infinitely loop any more!

But I had to update to Elastica's master branch to do it....

Change-Id: Id020f36f3670347a12b5e75b69040fccb69786b8
Teach config update script zero downtime updates.

Note that these zero downtime updates are far from zero time.  You can
read more about the idea here:
http://www.elasticsearch.org/blog/changing-mapping-with-zero-downtime/

Change-Id: Ib5b679ddd1b135f671a24beebd7060e0bba09012