Update databases/redis to 3.2.1.

Upgrade urgency HIGH: Critical fix to Redis Sentinel, due to 3.2.0
regression compared to 3.0.

Hey, this is Redis 3.2.1, and this release should bring some grain of
maturity to Redis 3.2. The list of commits following this note will tell
you the details, but the main things addressed in this release are the
following:

1. A critical bug in Sentinel was hopefully fixed. During the big 3.2
  refactoring of Redis Sentinel, in order to implement connection sharing
  to make Sentinel able to scale better (few Sentinels to monitor many
  masters), a bug was introduced that mis-counted the number of pending
  commands in the Redis link. This in turn resulted into an inability to
  talk with certain Redis instances. A common result of this bug was the
  inability of Redis Sentinel to reconfigure back the old master, after
  a failover, when it is reachable again, as the slave of the new master.
  This was due to the inability to talk with the old master at all.

2. BITFIELD bugs fixed.

3. GEO commands fixes on syntax errors and edge cases.

4. RESTORE now accepts dumps generated by older Redis versions.

5. Jemalloc now is really configured to save you memory, for a problem a
  change in the jemalloc configuration did not really survived when the
  3.2.0 release was finalized.

6. TTL and TYPE command no longer alter the last access time of a key, for
  LRU evictions purposes. A new TOUCH command was introduced *just* to
  update the access time of a key.

7. A bug was fixed in redis-cli, that connected to the instance running on
  the port 6379 if there was one, regardless of what was specified.

8. TCP keep alive is now enabled by default. This should fix most ghost
  connections problems without resulting in any practical change in
  otherwise sane deployments.

9. A Sentinel crash that could happen during failovers was fixed.

(fhajny)