Fix for use Ruby 1.8.x notation

$ ruby -v
ruby 1.8.7 (2012-02-08 patchlevel 358) [universal-darwin12.0]

$ redis-dump 
{"size":4,"ttl":-1,"key":"foo2,","type":"string","value":"bar2","db":0}
{"size":3,"ttl":-1,"key":"foo,","type":"string","value":"bar","db":0}