Core: clarify index removal log message
Core: Let the disk threshold decider take into account shards moving away from a node in order to determine if a shard can remain.

By taking this into account we can prevent that we move too many shards away than is necessary.

Closes #8538
Closes #8659
Core: separately log file deletions

Today, you can turn on lucene.iw TRACE logging, but that produces tons
of output.  This changes breaks out separate lucene.iw.ifd and
index.store.deletes logger components (TRACE), disabled by default, to
see what part of Elasticsearch is deleting index files.

Closed #8662

Closed #8603
release [1.4.1]
Update Documentation Feature Flags [1.4.1]
Prepare for next development iteration (1.4.2-SNAPSHOT)
Versions: Add 1.3.7 constants
[Docs] Fix missing comma in mapping
top_hits aggregation: Fail with a parse exception if `top_hits` agg is defined under a `nested` agg.

Closes #8668
Closes #8673
Test: predefine sort fields in mapping, otherwise during the test the field may not be found if it were to be introduced dynamically at index time.
[docs] explain default settings for parameters of decay functions

relates to #8624
[Docs] Fix missing new line
[Docs] fix consistency between examples
[TEST] With pipelining disabled requests can come back in any order

Closes #8697
Docs: Additional info about _score calculation

Description taken from http://www.elasticsearch.org/guide/en/elasticsearch/guide/current/multi-query-strings.html / 110_Multi_Field_Search/05_Multiple_query_strings.asciidoc

Closes #8635
[TEST] Relax constraints of breaker tests even more

They were very stringent, and add values in worst-case situations. The
new values are acceptable while still testing the functionality of the
breaker.

Conflicts:
	src/test/java/org/elasticsearch/common/breaker/MemoryCircuitBreakerTests.java
[TEST] Explicit wait for fielddata breaker to be cleared
Update daterange-aggregation.asciidoc

Clarified the date-math expressions on date range aggregations

Closes #8703
Docs: Grammar correction

Closes #8702
Add java documentation for aggregations

Buckets:
--------

* terms
* range
* global
* filter
* filters
* missing
* nested
* reverse nested
* children
* significant terms
* date range
* ip range
* range
* histogram
* date histogram
* geo distance
* geo hash grid

Metrics:
--------

* min
* max
* sum
* avg
* stats
* extended stats
* value count
* percentiles
* percentile rank
* cardinality
* geo bounds
* top hits
* scripted metric