* Fixed a bug in the performance counter query when run against SQL Server 2016 SP1-CU2. The performance counter DMV contains duplicate entries which are not handled by the query.

* Adding more stats related to workload groups.

* Adding new RG stats, removing "host" tag

* Removed workload group query

* Fixing some 2008 compat issues, removed the host field from the result set.

* Adding fixes for SQL Server 2008 compat around RG columns. Also converted perf counter query to support named instances.

* Included system databases in server properties, added backup/restore throughput counter, error counters, and user settable counters.

* Added more resource governor counters.

* Added Target and Total Server Memory counters.

* Removed the c_type tag from the performance counters query, added more documentation instead.

If unset, query_version is still treated as version 1 for compatibility.

Fixed a problem with sqlserver input where database properties are not returned by Telegraf when SQL Server has been set up with a case sensitive server-level collation.

* Added bugfix entry to CHANGELOG.md for sqlserver collation input fix.

Issue #1854

I added Rows/Logs max size counters for tracking databases that do not have autogrowth enabled. The counters return numbers in 8KB pages since there are a few special values (such as -1 for no max size) that can't directly be multiplied by 8192 to get size in bytes.

Also added Rows/Logs size in 8KB pages for comparison from the same system table. Even though it returns the same size as sizes from sys.dm_io_virtual_file_stats which are already collected.

This will basically make the root directory a place for storing the
major telegraf interfaces, which will make telegraf's godoc looks quite
a bit nicer. And make it easier for contributors to lookup the few data
types that they actually care about.

closes #564

closes #589