Precision query parameter not used to set current time in http_listener

[danielnelson]

Bug report

If a timestamp is not explicitly set, the time set by http_listener is not rounded to the precision in the precision query parameter. This behavior differs from InfluxDB.

Relevant telegraf.conf:

Enable http_listener

System info:

[Include Telegraf version, operating system name, and other relevant details]

Steps to reproduce:

1. curl -i -XPOST 'http://localhost:8186/write?precision=ms' --data-binary 'cpu value=42'

Expected behavior:

Rounded to milliseconds:

cpu value=42 1517883582041000000

Actual behavior:

Still in nanoseconds

cpu value=42 1517883582041456789