The `nested` aggregator should also resolve and use the parentFilter of the closest `reverse_nested` aggregator.

Closes #6994
Closes #7048
Aggregations: fixed value count so it can be used in terms order

Closes #7050
[TEST] Ignore Lucene40 codec
Docs: Add Drupal Search API Elasticsearch module

The module at drupal.org/project/elasticsearch has been abandoned. The Search API Elasticsearch module allows Drupal to use Elasticsearch as a backend for Search API.

Closes #7001
[TEST] All shards should be allocated before snapshotting.
Update request-body.asciidoc

Added link from `timeout` to time-units

Closes #6361
Add HierarchyCircuitBreakerService

Adds a breaker for request BigArrays, which are used for parent/child
queries as well as some aggregations. Certain operations like Netty HTTP
responses and transport responses increment the breaker, but will not
trip.

This also changes the output of the nodes' stats endpoint to show the
parent breaker as well as the fielddata and request breakers.

There are a number of new settings for breakers now:

`indices.breaker.total.limit`: starting limit for all memory-use breaker,
defaults to 70%

`indices.breaker.fielddata.limit`: starting limit for fielddata breaker,
defaults to 60%
`indices.breaker.fielddata.overhead`: overhead for fielddata breaker
estimations, defaults to 1.03

(the fielddata breaker settings also use the backwards-compatible
setting `indices.fielddata.breaker.limit` and
`indices.fielddata.breaker.overhead`)

`indices.breaker.request.limit`: starting limit for request breaker,
defaults to 40%
`indices.breaker.request.overhead`: request breaker estimation overhead,
defaults to 1.0

The breaker service infrastructure is now generic and opens the path to
adding additional circuit breakers in the future.

Fixes #6129

Conflicts:
	src/main/java/org/elasticsearch/index/fielddata/IndexFieldData.java
	src/main/java/org/elasticsearch/index/fielddata/IndexFieldDataService.java
	src/main/java/org/elasticsearch/index/fielddata/RamAccountingTermsEnum.java
	src/main/java/org/elasticsearch/index/fielddata/ordinals/GlobalOrdinalsBuilder.java
	src/main/java/org/elasticsearch/index/fielddata/ordinals/InternalGlobalOrdinalsBuilder.java
	src/main/java/org/elasticsearch/index/fielddata/plain/AbstractIndexOrdinalsFieldData.java
	src/main/java/org/elasticsearch/index/fielddata/plain/DisabledIndexFieldData.java
	src/main/java/org/elasticsearch/index/fielddata/plain/IndexIndexFieldData.java
	src/main/java/org/elasticsearch/index/fielddata/plain/NonEstimatingEstimator.java
	src/main/java/org/elasticsearch/index/fielddata/plain/PackedArrayIndexFieldData.java
	src/main/java/org/elasticsearch/index/fielddata/plain/ParentChildIndexFieldData.java
	src/main/java/org/elasticsearch/index/fielddata/plain/SortedSetDVOrdinalsIndexFieldData.java
	src/main/java/org/elasticsearch/node/internal/InternalNode.java
	src/test/java/org/elasticsearch/index/aliases/IndexAliasesServiceTests.java
	src/test/java/org/elasticsearch/index/codec/CodecTests.java
	src/test/java/org/elasticsearch/index/fielddata/AbstractFieldDataTests.java
	src/test/java/org/elasticsearch/index/fielddata/IndexFieldDataServiceTests.java
	src/test/java/org/elasticsearch/index/mapper/MapperTestUtils.java
	src/test/java/org/elasticsearch/index/query/IndexQueryParserFilterCachingTests.java
	src/test/java/org/elasticsearch/index/query/SimpleIndexQueryParserTests.java
	src/test/java/org/elasticsearch/index/query/guice/IndexQueryParserModuleTests.java
	src/test/java/org/elasticsearch/index/search/FieldDataTermsFilterTests.java
	src/test/java/org/elasticsearch/index/search/child/ChildrenConstantScoreQueryTests.java
	src/test/java/org/elasticsearch/index/similarity/SimilarityTests.java
Change logging level for circuit breaking to warn
[CORE] Support parsing lucene minor version strings

We parse the version that is shipped with the Lucene segments in order
to find the version of lucene that wrote a particular segment. Yet, some lucene
version ie:
 * 4.3.1 (Elasticsearch 0.90.2)
 * 4.5.1 (Elasticsearch 0.90.7)
 * 3.6.1 (pre Elasticsearch 0.90.0)

wrote illegal strings containing the minor version which causes IAE exceptions
being thrown from lucenes parsing method.

Closes #7055