closes #2299

* Add documentation to diskio plugin

* Update spelling, fix iops_in_progress unit

* Added GatherUserStatistics, row Uptime in gatherGlobalStatuses, and version fields & tags

* Updated README file

* pulling in latest from master

* ran go fmt to fix formatting

* fix unreachable code

* few fixes

* cleaning up and applying suggestions from sparrc

I don't like this behavior, but it's what InfluxDB accepts, so the
telegraf listener should be consistent with that.

I accidentally reverted this behavior when I refactored the telegraf
metric representation earlier in this release cycle.

* Document basic auth for haproxy

* Typo in haproxy readme

closes #2248

* Fixes change to the error api in the kafka project.

* Updated test to reflect the change.

* Update kafka to match master branch.

* Fix for broken librato output

These errors are delightful, but I'd rather avoid them:

```
Error parsing /etc/telegraf/telegraf.conf, line 2: field corresponding to `api_user' is not defined in `*librato.Librato'
```

* Fixed bad format from last commit

closes #2209

closes #2027

this is just a waste of cpu cycles, since telegraf converts all uints to
int64 anyways.

closes #1980

* Moved to using the inbuilt serializer.

* Remove Atomic variable as it is not required.

* Adjusted metric type in line with latest changes.

this basically reverts #887

at some point we might want to do some special handling of reloading
plugins and keeping their state intact, but that will need to be done at
a higher level, and in a way that is thread-safe for multiple input
plugins of the same type.

Unfortunately this is a rather large feature that will not have a quick
fix available for it.

fixes #1975
fixes #2102

* add clusterstats to elasticsearch input plugin

* add clusterstats to elasticsearch input plugin

* add clusterstats to elasticsearch input plugin

* add clusterstats to elasticsearch input plugin

* add clusterstats to elasticsearch input plugin

* responses to requested changes

* remove unnecessary recommendation

deals partially with #1973

see also https://github.com/vjeantet/grok/issues/17

closes #1898

* plugins/input/consul: moved check_id from regular fields to tags.

When service has more than one check sending data for both would overwrite each other
resulting only in one check being written (the last one). Adding check_id as a tag
ensures we will get info for all unique checks per service.

* plugins/inputs/consul: updated tests

closes #1763
closes #2017

* Update MySQL Readme to clarify connection string examples.

* Update mysql sample config to clarify connection string examples