[DOCS] Updated the mapping and field mapping docs to use the new format

Closes #6057
Lower initial sizing of sub aggregations.

We currently compute initial sizings based on the cardinality of our fields.
This can be highly exagerated for sub aggregations, for example if there is a
parent terms aggregation that is executed over a field that has a very long
tail: most buckets will only collect a couple of documents.

Close #5994
[DOCS] Added vertx elasticsearch integration
Correcting gramma
Limit the number of bytes that can be allocated to process requests.

This should prevent costly requests from killing the whole cluster.

Close #6050
Add a dedicated field data type for the _index field mapper.

This makes aggregations work on the _index field, and also allows to remove the
special facet aggregator for the _index field.

Close #5848
Update keyword-tokenizer.asciidoc
Removed Index Status API

The functionality of the index status API has been replaced by the recovery API.

Relates #4854
Renamed IndicesOptions#strict and IndicesOptions#lenient to make it clearer what they actually return, reused methods and introduced new one

Relates to #6059, where two new constants were introduced in IndicesOptions. There were already two constants there though, one of which we could have reused. This commit tries to unify them.
Add `shard_min_doc_count` parameter for significant terms similar to `shard_size`

Significant terms internally maintain a priority queue per shard with a size potentially
lower than the number of terms. This queue uses the score as criterion to determine if
a bucket is kept or not. If many terms with low subsetDF score very high
but the `min_doc_count` is set high, this might result in no terms being
returned because the pq is filled with low frequent terms which are all sorted
out in the end.

This can be avoided by increasing the `shard_size` parameter to a higher value.
However, it is not immediately clear to which value this parameter must be set
because we can not know how many terms with low frequency are scored higher that
the high frequent terms that we are actually interested in.

On the other hand, if there is no routing of docs to shards involved, we can maybe
assume that the documents of classes and also the terms therein are distributed evenly
across shards. In that case it might be easier to not add documents to the pq that have
subsetDF <= `shard_min_doc_count` which can be set to something like
`min_doc_count`/number of shards  because we would assume that even when summing up
the subsetDF across shards `min_doc_count` will not be reached.

closes #5998
closes #6041
Node version sometimes empty in _cat/nodes
closes #5480
[DOCS] Update nodes documentation with all headers

Adds a table with the exhaustive list of all available headers with a brief description (mostly from `org.elasticsearch.rest.action.cat.RestNodesAction`) so that people do not need to go searching for them in the code like I did, or search through `nodes?help`.
Changed the respnose structure of the percentiles aggregation where now all the percentiles are placed under a `values` object (or `values` array in case the `keyed` flag is set to `false`

Closes #5870
clarify that CMS defaults change is coming in 1.2
Fix _cat/allocation rest test

The rest test for _cat/allocation was failing due to a regular
expression not accounting for space-padded right-justified text.

Also added Improvements to regular expressions to be smarter about optional values
and to use '+' instead of '*' where applicable.
Fix stack overflow in _cat/recovery test.

This fixes a stack overflow in the test for the _cat/recovery API.
The regular expression that tests the response body was modified to
handle large responses properly.
Integration tests for benchmark API.

- Randomized integration tests for the benchmark API.
- Negative tests for cases where the cluster cannot run benchmarks.
- Return 404 on missing benchmark name.
- Allow to specify 'types' as an array in the JSON syntax when describing a benchmark competition.
- Don't record slowest for single-request competitions.

Closes #6003, #5906, #5903, #5904
it's safe to use OneMerge.getTotalBytesSize (fixed in LUCENE-4775)
Fix for benchmark test

- Fix bug where repeatedly calling computeSummaryStatistics() could
  accumulate some values incorrectly.
- Fix check for number of responsive nodes on list is <= number of
  candidate benchmark nodes.
- Add public getters for summary statistics
- Add javadoc for new getters
- Add javadoc comments about API use
The percolator needs to deleted percolator documents into account when running in near realtime mode.

This bug only occurs in non-realtime mode when query, filter, facet or aggs is used.

Closes #5843
Closes #5840