Rewrote post-filter.asciidoc

Closes #5166
Update translog.asciidoc

Documented `index.gateway.local.sync`
[BUILD] Add profile that skips all validations

This commit adds a profile that skips all validation ie.
 - nocommit / tabs checking
 - forbidden API checks
 - license headers

It's not active by default but can easily be activated with
  `mvn -Pdev` or in the `~/.m2/settings.xml`

for reference see:
  http://maven.apache.org/guides/introduction/introduction-to-profiles.html
[TEST] Increased logging and make use of prepareCreate and assertAcked
[TEST] All shards should be allocated before snapshotting & restoring
cluster block with auto create index bulk action can cause bulk execution to not return
when there is a cluster block (like no master yet discovered), the bulk action doesn't properly catch the exception of inner execute to notify the listener, causing the bulk operation to hang
closes #7086
_geo_distance sort: allow many to many geo point distance

Add computation of disyance to many geo points. Example request:

```
{
  "sort": [
    {
      "_geo_distance": {
        "location": [
          {
            "lat":1.2,
            "lon":3
          },
          {
             "lat":1.2,
            "lon":3
          }
        ],
        "order": "desc",
        "unit": "km",
        "sort_mode": "max"
      }
    }
  ]
}
```

closes #3926
[TEST] Reduce number of updates and wait after 1st NoNodeException.
Generate timestamp when path is null

Index process fails when having `_timestamp` enabled and `path` option is set.
It fails with a `TimestampParsingException[failed to parse timestamp [null]]` message.

Reproduction:

```
DELETE test
PUT  test
{
    "mappings": {
        "test": {
            "_timestamp" : {
                "enabled" : "yes",
                "path" : "post_date"
            }
        }
    }
}
PUT test/test/1
{
  "foo": "bar"
}
```

You can define a default value for when timestamp is not provided
within the index request or in the `_source` document.

By default, the default value is `now` which means the date the document was processed by the indexing chain.

You can disable that default value by setting `default` to `null`. It means that `timestamp` is mandatory:

```
{
    "tweet" : {
        "_timestamp" : {
            "enabled" : true,
            "default" : null
        }
    }
}
```

If you don't provide any timestamp value, indexation will fail.

You can also set the default value to any date respecting timestamp format:

```
{
    "tweet" : {
        "_timestamp" : {
            "enabled" : true,
            "format" : "YYYY-MM-dd",
            "default" : "1970-01-01"
        }
    }
}
```

If you don't provide any timestamp value, indexation will fail.

Closes #4718.
Closes #7036.
Search Exists API: Checks if any matching documents exist for a given query

Implements a new Exists API allowing users to do fast exists check on any matched documents for a given query.
This API should be faster then using the Count API as it will:
 - early terminate the search execution once any document is found to exist
 - return the response as soon as the first shard reports matched documents

closes #6995
Mappings: Fix `copy_to` behavior on nested documents.

Today, `copy_to` always copies a field to the current document, which is often
wrong in the case of nested documents. For example, if you have a nested field
called `n` which has a sub-field `n.source` whose content should be copied to
`target`, then the latter field should be created in the root document instead
of the nested one, since it doesn't have `n.` as a prefix. On the contrary, if
you configure the destination field to be `n.target`, then it should go to the
nested document.

Close #6701
Aggregations: Fix infinite loop in the histogram reduce logic.

The histogram reduce method can run into an infinite loop if the
Rounding.nextRoundingValue value is buggy, which happened to be the case for
DayTimeZoneRoundingFloor.

DayTimeZoneRoundingFloor is fixed, and the histogram reduce method has been
changed to fail instead of running into an infinite loop in case of a buffy
nextRoundingValue impl.

Close #6965
Update fielddata-fields.asciidoc
Docs: add 1.4.0 label to many to many geo distance sort
[DOCS] fixed small typo in percolate.asciidoc
Function score query: Add missing whitespace when throwing exception

DecayFunctionParser throws a parse exception with a string containing "scaleand origin", this fixes the spacing issue.
Removed support for aliases as part of index settings

Now that we have explicit support for aliases when creating indices and as part of index templates, we may remove support for aliases (only names) as part of index settings. This is partially breaking as the following calls:

curl -XPUT localhost:9200/index -d '{
  "settings" : {
    "aliases" : [ "alias1"]
  }
}

and

curl -XPUT localhost:9200/index -d '{
  "settings" : {
    "index.aliases" : [ "alias1"]
  }
}

were previously supported and will need to be replaced with

curl -XPUT localhost:9200/index -d '{
  "aliases" : {
    "alias1": {}
  }
}

Closes #5545
[TEST] check breaker reset after parent trip instead of trip count
Sort: Make `ignore_unmapped` work for cross-index queries.

Close #2255
Aggregations Added Filters aggregation

A multi-bucket aggregation where multiple filters can be defined (each filter defines a bucket). The buckets will collect all the documents that match their associated filter.

This aggregation can be very useful when one wants to compare analytics between different criterias. It can also be accomplished using multiple definitions of the single filter aggregation, but here, the user will only need to define the sub-aggregations only once.

Closes #6118