First, this breaks backwards compatibility!
* Removed /_cluster/nodes/stats endpoint
* Excpect the stats types not as parameters, but as part of the URL
* Returning all indices stats by default, returning all nodes stats by default
* Supporting groups & types in nodes stats now as well
* Updated documentation & tests accordingly
* Allow level parameter for "shards" and "indices" (cluster does not make sense here)
Closes#4057
This adds the field data circuit breaker, which is used to estimate
the amount of memory required to load field data before loading it. It
then raises a CircuitBreakingException if the limit is exceeded.
It is configured with two parameters:
`indices.fielddata.cache.breaker.limit` - the maximum number of bytes
of field data to be loaded before circuit breaking. Defaults to
`indices.fielddata.cache.size` if set, unbounded otherwise.
`indices.fielddata.cache.breaker.overhead` - a contast for all field
data estimations to be multiplied with before aggregation. Defaults to
1.03.
Both settings can be configured dynamically using the cluster update
settings API.