[Redis-Session] - Add the expire command on create & set methods to allo...

Add the expire command on create & set methods to allow the the use of events, like expire emit providing by redis. If you just precise a ttl, the resource is well deleted but no event is triggered

Now i can 
``` javascript 

// Create the session
session.create({
    app : rsapp,
    id  : idUser,
    ip  : ipUser,
    ttl : 10,
    d   : {
        cartToken: cartAdded.cartToken,
        cartUid: cartAdded.uid
    }}, function (err, sessionGen) {
            cartAdded
                ._set('sessionToken', sessionGen.token).update();
});

rsKeyBeg = 'rs:'+yournamespace+':';

// Session is removed, an event is emitted from the redis server, and I can remove My cart
var eventNotifier = new RedisNotifier(redis, {
    redis : { host : 1234, port : locahost},
    expired : true,
    del : true,
    logLevel : 'INFO' //Defaults To INFO
});

eventNotifier.on('message', function(pattern, channelPattern, emittedKey) {
    var channel = this.parseMessageChannel(channelPattern);
    switch(channel.key) {
     case 'expired':
         cart.removeBySessionToken(emittedKey.replace(rsKeyBeg,''));
         break;
     default:
        logger.debug("Unrecognized Channel Type:" + channel.type);
     }
});

// My cart is removed

```