Fix typo in similarity docs

DRF similarity -> DFR similarity
Allow specifying nested fields in simple_query_string

Fixes #5091
[docs] fixed errors in aggs docs
- error in nested aggs example
- error in terms aggs example
[TEST] added missing wait for yellow in put warmer REST test
Added the `DistanceUnit.NAUTICALMILES` enumeration
label with the corresponding *NM* and *nmi* unit
suffixes. Update the docs to match.

Closes #5085
Update get.asciidoc

Minor improvements.

curl -XHEAD doesn't actually print anything so I've changed to use -I which actually prints the headers received.
[DOCS] improved get docs

- added _version to response
- exists call use -XHEAD with -i flag to include headers in the output
Make sure that parent type is created explicitly.
Cleaned up the p/c integration tests to use shorter mapping definition, ensureGreen() and .get()
Fixed issue where highlighting in percolate existing doc api doesn't work (no highlight snippets)
code coverage hookup
Add preserve original token option to ASCIIFolding

Closes #4931
Add support for `lowercase_expanded_terms` flag to simple_query_string

Default the flag to true, making simple_query_string behave similarly to
query_string

Fixes #5008
Fix license header for SimpleQueryParser
Enable percolation for nested documents

closes #5082
Optimize multiple cluster state processing on receiving nodes
Nodes that receive the cluster state, and they have several of those pending, can optimize and try and process potentially only one of those.
closes #5139
Added support for aliases to create index api

It is now possible to specify aliases during index creation:

curl -XPUT 'http://localhost:9200/test' -d '
{
    "aliases" : {
        "alias1" : {},
        "alias2" : {
            "filter" : { "term" : {"field":"value"}}
        }
    }
}'

Closes #4920
[DOCS] Remove clear flag from node-stats as it is not used anymore
Source filtering with wildcards broken when given multiple patterns

```
curl -XPUT 'http://localhost:9200/twitter/tweet/1' -d '{
    "user" : "kimchy",
    "post_date" : "2009-11-15T14:12:12",
    "message" : "trying out Elasticsearch", "retweeted": false
}'
```

No source fields delivered:

```
curl -XGET 'http://localhost:9200/twitter/tweet/1?_source=*.id,retweeted&pretty=yes'
```

`retweeted` returned:

```
curl -XGET 'http://localhost:9200/twitter/tweet/1?_source=retweeted,*.id&pretty=yes'
```

Closes #5132.
Closes #5133.
Fix typo
Set permission in debian postinst script correctly

The old post installation script on debian set all data to
644 inside of /etc/elasticsearch, which does not work, when
there are subdirectories

Closes #3820