Immediate update when creating streams.

[volt42]

When a stream is created with polling it would be nice if the system immediately fetched the latest value from the URI, instead of waiting for one interval of time before getting the first one. I am guessing that it is just a matter of starting a timer at 0 the first time, instead of the given interval.

[gxlzlihao]

Ok, I will do this minor change, I will let it send a {probe} to the poller when it is created.