Print a warning to STDERR if Redis version is less than 2.1.3
Print a warning to STDERR if Redis version is less than 2.1.3

Prior to v2.1.3, any writes to keys with an expire/TTL set were
completely deleted before the write took place.

jimeh/redistat,drianpauL/redistat,ukd1/redistat,jylamont/redistat,felipeclopes/redisrank