Test: Python doesn't support atomic groups in regexes. Removing from cat.recovery
Upgrade to netty 3.9.1
closes #6331
[TESTS] Add get snapshot status test for partial snapshots
[DOCS] Java 7 is required since 1.2.0
Aggregations: Fixed bug in top_hits aggregation to not fail with NPE when shard results are empty.

The top_hits aggregation returned an empty InternalTopHits instance with no fields set when there were no result, causing reduce and serialization errors down the road. This is fixed by setting all required fields when a there are no results.

Closes #6346
Aggregations: added pagination support to `top_hits` aggregation by adding `from` option.

Closes #6299
Docs: Tidied percolate.asciidoc
[BUILD] Fix compile error
Have a dedicated join timeout that is higher than ping.timeout for node join
Using ping.timeout, which defaults to 3s, to use as a timeout value on the join request a node makes to the master once its discovered can be too small, specifically when there is a large cluster state involved (and by definition, all the buffers and such on the nio layer will be "cold"). Introduce a dedicated join.timeout setting, that by default is 10x the ping.timeout (so 30s by default).
closes #6342
Aggregations: Take the 'from' into account when getting a fetched hit (InternalSearchHit). Hits before the 'from' are included in each shard result.
Added minimum_should_match to has_child queries with score_mode != none
Inlined code
Decrement parentWeight.remaining before checking min_should_match
Take minShouldMatch into account in equals(), hashCode() and toString()
Renamed min_should_match to minimum_children
Added support for minimum_children in HasChildQueryBuilder
Implemented CountChildrenConstantScoreQuery as a hybrid between
ChildrenConstantScoreQuery and ChildrenQuery.  Intended only
for has_child filter or has_child queries without scoring
when minimum_children > 1 is specified.
Fixed the license header
Fixed ChildrenQueryTests
Added YAML tests for has_child filter/query