Time bug in stats related to "Daylight saving time"

[johnnyjinjing]

It seems to have a bug with the time in stats when the query time period includes a change in daylight saving time (for example, from PST to PDT or vice versa). See the output below for more details.

[{"date":"2016-11-01T23:00:00.000Z","universal":1478041200000,"count":0},{"date":"2016-11-02T23:00:00.000Z","universal":1478127600000,"count":0},{"date":"2016-11-03T23:00:00.000Z","universal":1478214000000,"count":0},{"date":"2016-11-04T23:00:00.000Z","universal":1478300400000,"count":0},{"date":"2016-11-05T23:00:00.000Z","universal":1478386800000,"count":0},{"date":"2016-11-07T00:00:00.000Z","universal":1478476800000,"count":0},{"date":"2016-11-08T00:00:00.000Z","universal":1478563200000,"count":0},{"date":"2016-11-09T00:00:00.000Z","universal":1478649600000,"count":0},{"date":"2016-11-10T00:00:00.000Z","universal":1478736000000,"count":0},{"date":"2016-11-11T00:00:00.000Z","universal":1478822400000,"count":0},{"date":"2016-11-12T00:00:00.000Z","universal":1478908800000,"count":1},{"date":"2016-11-13T00:00:00.000Z","universal":1478995200000,"count":0},{"date":"2016-11-14T00:00:00.000Z","universal":1479081600000,"count":0},{"date":"2016-11-15T00:00:00.000Z","universal":1479168000000,"count":1}]

The result above is from a query with the custom time range from "2016-11-01T00:00:00.000Z" to "2016-11-15T00:00:00.000Z". The time changes on Nov 6 from PDT to PST, and the time before Nov 7 are shifted by 1 hour.

I will send to PR with the solution.