Fixed typo in TransportAction log line
[TEST] Remove indentation on indices.stats test setups

The new indices.stats tests have the setup section indented, which
can cause problems for some yaml parsers.
significant terms: fix json response

Commit fbd7c9aa5d6c1c introduced a regression that caused
the min_doc_count to be equal to the number of documents in the
background set. As a result no buckets were built when the
response for significant terms was created.
This only affected the final XContent response.

closes #6535
[DOCS] Fixed json example in nested-aggregation.asciidoc
REST API: Allow to configure JSONP/callback support

Added the http.jsonp.enable option to configure disabling of JSONP responses, as those
might pose a security risk, and can be disabled if unused.

This also fixes bugs in NettyHttpChannel
* JSONP responses were never setting application/javascript as the content-type
* The content-type and content-length headers were being overwritten even if they were set before

Closes #6164
Mapping: Fix possibility of losing meta configuration on field mapping update

The TTL, size, timestamp and index meta properties could be lost on an
update of a single field mapping due to a wrong comparison in the
merge method (which was caused by a wrong initialization, which marked
an update as explicitely disabled instead of unset.

Closes #5053
Java API: BulkRequest#add(Iterable) to support UpdateRequests

Closes #6551
[TEST] Added (trace) logging to testGetFields_complexField
Mappings: Allow _version to use `disk` as a doc values format.

VersionFieldMapper.defaultDocValuesFormat claims that the default is `disk`.
This is not used to choose the DV format in the index but for mappings
serialization in order to know when the _version doc values format is
different from the default format. This made it impossible to use the `disk`
doc values format since mappings would never retain that information at
serialization time.

Close #6523
Index field names of documents.

The `exists` and `missing` filters need to merge postings lists of all existing
terms, which can be very costly, especially on high-cardinality fields. This
commit indexes the field names of a document under `_field_names` and reuses it
to speed up the `exists` and `missing` filters.

This is only enabled for indices that are created on or after Elasticsearch
1.3.0.

Close #5659
Fielddata: Merge ordinals APIs into BytesValues.WithOrdinals.

Mid-term we should switch from `BytesValues` to Lucene's doc values APIs, in
particular the `SortedSetDocValues` class. While `BytesValues.WithOrdinals` and
SortedSetDocValues expose the same functionality, `BytesValues.WithOrdinals`
exposes its ordinals via a different `Ordinals.Docs` object while
`SortedSetDocValues` exposes them on the same object as the one that holds the
values. This commit merges ordinals into `BytesValues.WithOrdinals` in order to
make both classes even closer.

Global ordinals were a bit tricky to migrate so I just changed them to use
Lucene's OrdinalMap that will soon (LUCENE-5767, scheduled for 4.9) have the
same optimizations as our global ordinals.

Close #6524
Fielddata: Move `getTermsEnum` from `AtomicFieldData` to `BytesValues.WithOrdinals`.

Similarly to `SortedSetDocValues.termsEnum()`.

Relates to #6524
Fielddata: Remove BytesValues.WithOrdinals.currentOrd and copyShared.

These methods don't exist in Lucene's sorted set doc values.

Relates to #6524
Docs: Rewrote the filtered query docs to be clearer

Closes #1688
Client intermediate interface removal follow-up

After #6517 we ended up registering all of the actions (included admin ones) to the NodeClient.
Made sure that only the proper type of Action instances are registered to each client type.
Also fixed some compiler warnings: unused members, imports and non matching generic types.

Closes #6563
REST api: made it possible to copy the REST headers from REST requests to the corresponding TransportRequest(s)

Introduced the use of the FilterClient in all of the REST actions, which delegates all of the operations to the internal Client, but makes sure that the headers are properly copied if needed from REST requests to TransportRequest(s) when it comes to executing them.

Added new abstract handleRequest method to BaseRestHandler with additional Client argument and made private the client instance member (was protected before) to force the use of the client received as argument.

The list of headers to be copied over is by default empty but can be extended via plugins.

Closes #6513
Add Groovy as a scripting language, add sandboxing for Groovy

Sandboxes the groovy scripting language with multiple configurable
whitelists:

`script.groovy.sandbox.receiver_whitelist`: comma-separated list of string
classes for objects that may have methods invoked.
`script.groovy.sandbox.package_whitelist`: comma-separated list of
packages under which new objects may be constructed.
`script.groovy.sandbox.class_whitelist` comma-separated list of classes
that are allowed to be constructed.

As well as a method blacklist:

`script.groovy.sandbox.method_blacklist`: comma-separated list of
methods that are never allowed to be invoked, regardless of target
object.

The sandbox can be entirely disabled by setting:

`script.groovy.sandbox.enabled: false`
Re-shade MVEL as a dependency
Docs: Updated cluster health docs
Refactored AckedClusterStateUpdateTask & co. to remove code repetitions in subclasses

Made AckedClusterStateUpdateTask an abstract class instead of an interface, which contains the common methods.
Also introduced the AckedRequest interface to mark both AcknowledgedRequest & ClusterStateUpdateRequest so that the different ways of updating the cluster state (with or without a MetaData*Service) can share the same code.
Removed ClusterStateUpdateListener as we can just use its base class ActionListener instead.

Closes #6559