=== Stats, info, and `cat` changes

==== Sigar removed

We no longer ship the Sigar library for operating system dependent statistics,
as it no longer seems to be maintained.  Instead, we rely on the statistics
provided by the JVM.  This has resulted in a number of changes to the node
info, and node stats responses:

* `network.*` has been removed from nodes info and nodes stats.
* `fs.*.dev` and `fs.*.disk*` have been removed from nodes stats.
* `os.*` has been removed from nodes stats, except for `os.timestamp`,
  `os.load_average`, `os.mem.*`, and `os.swap.*`.
* `os.mem.total` and `os.swap.total` have been removed from nodes info.
* `process.mem.resident` and `process.mem.share` have been removed from node stats.

==== Removed `id_cache` from stats apis

Removed `id_cache` metric from nodes stats, indices stats and cluster stats
apis. This metric has also been removed from the shards cat, indices cat and
nodes cat apis. Parent/child memory is now reported under fielddata, because
it has internally be using fielddata for a while now.

To just see how much parent/child related field data is taking, the
`fielddata_fields` option can be used on the stats apis. Indices stats
example:

[source,js]
--------------------------------------------------
GET /_stats/fielddata?fielddata_fields=_parent
--------------------------------------------------

==== Percolator stats

The total time spent running percolator queries is now called `percolate.time`
instead of `percolate.get_time`.

==== Cluster state REST API

The cluster state API doesn't return the `routing_nodes` section anymore when
`routing_table` is requested. The newly introduced `routing_nodes` flag can be
used separately to control whether `routing_nodes` should be returned.

==== Index status API

The deprecated index status API has been removed.

==== `cat` APIs verbose by default

The `cat` APIs now default to being verbose, which means they output column
headers by default. Verbosity can be turned off with the `v` parameter:

[source,sh]
-----------------
GET _cat/shards?v=0
-----------------

