Update Go version to 1.9.1?

For now there is 1.6.2, it is released 2016/02/17, more than 1.5 year ago.

Can you update go version to latest one please?

The time package now transparently tracks monotonic time in each Time value, making computing durations between two Time values a safe operation in the presence of wall clock adjustments. For example, this code now computes the right elapsed time even across a leap second clock reset:

start := time.Now()
elapsed := time.Since(start)