Update node-redis package

[snird]

Currently using 0.12.1 of redis package, which is a very old and obsolete version.
Furthermore: it poses a challenge as it cause bugs and instability with node version 4.0 and greater.

As the node-redis project came back to life, and is highly maintained, we can keep using it as the base driver and drop issue #21 to move to ioredis.