45d0a772e19e93e90fd18ce4652da66672b0420f

Based off https://gerrit-review.googlesource.com/#/c/52190, but implementing the final suggestion of indexing raw delta counts and allowing arbitrary range queries off of those. Also upgrade Lucene to 4.8.1 as this was released since the last schema change (which was on 4.7.0). Change-Id: Ia8a677e71e133f68eced4c5394df1d23efe7f12a
Description
RETIRED, Gerrit as used by OpenStack