During issue #2215 it was highlighted that the current behavior where
rules without a comment are ignored is confusing for several users.

This commit improves the documentation and adds a NOTE to the sample
config to clarify the behavior for new users.

Tweak formatting of `LogicalDisk` counter array to have one entry per
line.

closes #1433

closes #2466

closes #2178

closes #2071

closes #2414

fixes #2380

closes #2390
closes #2404

fixes #2282

The docker engine-api package we use needs golang 1.7+, see:
https://github.com/docker/engine-api/pull/382#issuecomment-244512952

So telegraf won't compile without 1.7

closes #2339

Also, ensure pidfile perms are 644

closes #1516 
closes #1711 
closes #1721 
closes #1526 

* Procstat: don't cache PIDs

Changed the procstat input plugin to not cache PIDs. Solves #1636.
The logic of creating a process by pid was moved from `procstat.go` to
`spec_processor.go`.

* Procstat: go fmt

* procstat: modify changelog for #2206

closes #2244
closes #1547

this defer function was causing telegraf to call os.Exit(0) instead of
panicking when it was supposed to.

closes #2341

closes #2356

* ceph: maps are already refs, no need to use a pointer

* ceph: pgmap_states are represented in a single metric "count", differenciated by tag

* Update CHANGELOG

* Update README.md

* Add lock support to the IPtables input plugin

* Update iptables.go

Doc cleaning