More Like This Query: values of a multi-value fields are compared at the same level.

Previously, More Like This would create a new mlt query for each value of a
multi-value field. This could result in all the values of the field to be
selected, which defeats the purpose of More Like This. Instead, the correct
behavior is to generate only one mlt query for all the values of the field.
This commit provides the correct behavior for More Like This DSL. The fix for
More Like This API will be coming in another commit.

Closes #6310
[DOCS] Fixed typo in IndexRequestBuilder Javadocs
[DOCS] Update index docs to match changes in IndexResponse class

IndexResponse.id() ->  IndexResponse.getId()
[DOCS] fixed urls in nodes-stats docs
Remove support for field names in node_stats url

Field names ended up making the urls too long, fields are still supported as query string parameters though (same as indices stats)
[DOCS] Improved readability of multi-match query docs
[BUILD] Calculate the full path ahead of time
Revert "[BUILD] Calculate the full path ahead of time"
Revert "[BUILD] Promote artifacts from strings to their own type"

This reverts commit dcd4ba0654eb6780235718092969c2f9e6b38775.
This reverts commit 00d7eb3c0a6eefdb5947d07b18cf071ba538d696.
Routing: Restore shard routing.

Routing has been inadvertly changed in #5562 resulting in documents going to
different shards in 1.2. This is a terrible bug because an indexing request
would not necessarily go to the same shard anymore, potentially leading to
duplicates.

Close #6391
Translog: Revert unlimited flush_treshold_ops for translog

This commit reverts the commit for issue #5900 introduced
in `1.2.0`. The unlimited translog size can cause memory pressure
on ES instances with low memory and high indexing load.

Closes #6377
Aggregations: Adds GeoBounds Aggregation

The GeoBounds Aggregation is a new single bucket aggregation which outputs the coordinates of a bounding box containing all the points from all the documents passed to the aggregation as well as the doc count. Geobound Aggregation also use a wrap_logitude parameter which specifies whether the resulting bounding box is permitted to overlap the international date line.  This option defaults to true.

This aggregation introduces the idea of MetricsAggregation which do not return double values and cannot be used for sorting.  The existing MetricsAggregation has been renamed to NumericMetricsAggregation and is a subclass of MetricsAggregation.  MetricsAggregations do not store doc counts and do not support child aggregations.

Closes #5634
Add [1.2.1] Release