Remove PSET commands to restore Redis 2.4.8 compatibility

Hello @x-ma, 

Please review the following commits I made in branch 'jamie-redis-compat'.

3ee0c64f448c160467c2522ee316cc42a73ba74d (2013-07-22 17:28:21 -0700)
Remove PSET commands to restore Redis 2.4.8 compatibility


R=@x-ma