Update redis to 0.8.1

[coderarity]

This fixes an issue with socket.io on Nodejitsu, since the hiredis optional dependency was removed in this version or node_redis. hiredis fails to build properly on SmartOS and npm fails when the hiredis optional dependency doesn't build correctly. Thanks!

[3rd-Eden]

@coderarity socket.io is no longer having redis as a dependency as of f7f219d

Until @guille releases a new version you can advise users to the git url instead of version numbers in their package.json.