PCT-506 Fixed lost sample

The idea is as follows.
c003- 1 to 5 will set the first 5 metrics, but the first one is not being added since firstVal in Stats struct is true.
c003-r is the metric number 6 as in the original and c003-6~11 are the new metrics for the second interval if 5 seconds.
```
func (s *AggregatorTestSuite) TestC003(t *C) {
	interval := int64(5)
```
When the second interval starts, Reset method is being executed and for this second interval we will have all the 5 metrics without loosing any data point.

Suppose the aggregator starts at h:m:15. We already lost the first 14 seconds, right?
Well, at the second minute, Reset method will start doing its job and all datapoints will be collected.