adding llen, lpush, lpop, rpush, rpop
adding the new functions to the readme and adding me as a contributor
adding lindex and lset
adding lpushx and rpushx
adding events to Item when elements are added or removed from the list
correcting rpush and lpush as they were not as node-redis works (multiple arguments not array for values)
adding an helper function for lpop and rpop
making the callback optionnal and launched on process.nextTick
adding blpop and brpop
Merge pull request #7 from lahabana/master

Adding some of the list functions