Update changelog

Author: danielnelson

CHANGELOG.md

@@ -102,6 +102,7 @@
 - [#3149](https://github.com/influxdata/telegraf/issues/3149): Don't fail parsing zpool stats if pool health is UNAVAIL on FreeBSD.
 - [#2672](https://github.com/influxdata/telegraf/issues/2672): Fix NSQ input plugin when used with version 1.0.0-compat.
 - [#2523](https://github.com/influxdata/telegraf/issues/2523): Added CloudWatch metric constraint validation.
+- [#3179](https://github.com/influxdata/telegraf/issues/3179): Skip non-numerical values in graphite format.
 
 ## v1.3.5 [2017-07-26]