Sysstat plugin needs LANG=C or similar locale

[NerdyProjects]

Bug report

When running on a system with default locale de_DE (e.g. one, where numbers are formatted differently), the sysstat plugin output can not be parsed:

2016/10/17 15:10:49 ERROR in input [sysstat]: strconv.ParseFloat: parsing "13,11": invalid syntax
strconv.ParseFloat: parsing "139,00": invalid syntax
strconv.ParseFloat: parsing "0,00": invalid syntax

(...)

Putting LANG=C in /etc/default/telegraf fixes the problem.

System info:

Debian GNU/Linux 8 (jessie)
Linux banana 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-1 (2016-03-06) x86_64 GNU/Linux
telegraf 0.1-1 amd64

Steps to reproduce:

1. make sure, you have the de_DE.UTF-8 locale installed (`echo de_DE.UTF-8 UTF-8 >> /etc/locale.gen; locale-gen)
2. LANG=de_DE.UTF-8 telegraf -debug

Expected behavior:

No errors appear

Actual behavior:

ParseFloat is not able to parse the sysstat output

Additional info:

Proposal:

Document this behaviour or better set a default compatible locale. I am not sure if this is the proper solution.