Atmosphere-tracking-id not set with SerializedClient.

Hi Jeanfrancois

I found an issue with the SerializedClient. I thought I made it compatible with the AtmosphereClient but somehow the tracking-id is not set on subsequent GETs.

The test is a modified NoMessageLostTest, that does not suspend and does log the resource's.uuid(). It is a new random one on every connect. 

The same test with an AtmosphereClient nicely puts the same UUID always.

Could you have a look, I can't fix it myself, I tried.

Regards, Christian.