Imported Upstream version 2.8.18
Merge tag 'upstream/2.8.18'

Upstream version 2.8.18

* tag 'upstream/2.8.18':
  Imported Upstream version 2.8.18
New upstream release.
Sync debian/redis.conf.
Bump Standards-Version to 3.9.6.
releasing package redis version 2:2.8.18-1