[SPEC] Added level param to cluster.node_stats and indices.stats
[SPEC] Updated cluster.state spec
[SPEC] Added level param to cluster.state
Revert "[SPEC] Added level param to cluster.state"

This reverts commit 06e5f3dd6ff3db5c30b67e1d4eb80ff759533f93.
Adds a new coerce flag for numeric field mappings which is defaulted to true.
When set to false a new strict mode of parsing is employed which
a) does not permit numbers to be passed as JSON strings in quotes
b) rejects numbers with fractions that are passed to integer, short or long fields.

Closes #4117
Tribe Node
The tribes feature allowed to create a tribe node that can act as a federated client across multiple clusters.

The tribe node configuration looks something like this:

```
tribe.t1.cluster.name: cluster1
tribe.t2.cluster.name: cluster2
```

The configuration above configure connections to 2 clusters, named `t1`, `t2`. It creates a "node" client to each (so by default, above, multicast discovery is used). The settings for each node client is extracted from the `tribe.[tribe_name]` prefix.

The way the tribe node works is by merging the cluster state from each cluster, and creating a merged view of all clusters. This means all operations work the same, distributed search, suggest, percolation, indexing, ... .

The merged view drops conflicted indices and picks one of them if there are 2 indices with the same name across multiple clusters.

By default, read and write operations are allowed. Master level read operations (cluster state for example), require setting the local flag to true (since there is no elected master). Master level write operations are not allowed (create index, ...).

The tribe node can be configured to block write operations `tribe.blocks.write` to `true`, and metadata operations by setting `tribe.blocks.metadata` to `true`.
closes #4708
[DOCS] Update cat/indices to reflect ?pri flag
apply comments on tribe code
add similar concrete path trie tests resolution
clean the params before running the next test
[DOCS] Added docs for tribe node

Related #4708
[DOCS] Fixed link to tribe.asciidoc
Remove `ElasticsearchInterruptedException` and handle interrupt state
correctly.

InterruptedExceptions should be handled by either rethrowing or
restoring the interrupt state (i.e. calling
`Thread.currentThread().interrupt()`). This is important since the
caller of the is method or subequent method calls might also be
interested in this exception. If we ignore the interrupt state the
caller might be left unaware of the exception and blocks again on
a subsequent method.

Closes #4712
Default to not accepting type wrapper in indexing requests

Currently it is possible to index a document as:

```
POST /myindex/mytype/1
{ "foo"...}
```

or as:

```
POST /myindex/mytype/1
{
    "mytype": {
        "foo"...
    }
}
```

This makes indexing non-deterministic and fields can be misinterpreted
as type names.

This changes makes Elasticsearch accept only the first form by default,
ie without the type wrapper. This can be changed by setting
`index.mapping.allow_type_wrapper` to `true`` when creating the index.

Closes #4484
Improve support for partial snapshots

Fixes #4701. Changes behavior of the snapshot operation. The operation now fails if not all primary shards are available at the beginning of the snapshot operation. The restore operation no longer tries to restore indices with shards that failed or were missing during snapshot operation.