Update forbidden-apis to 1.5.1 and remove the relaxed missing classes error.
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' of https://github.com/elasticsearch/elasticsearch
Merge branch 'master' of https://github.com/elasticsearch/elasticsearch
Update forbidden-apis to 1.6
Update forbidden-apis to 1.6
Update forbidden-apis to 1.6
Merge branch 'master' of https://github.com/uschindler/elasticsearch into forbiddenapis-1.6-update
Added an option to add arbitrary headers to the client requests

The headers are key/value pairs defined in the settings under the `request.headers` namespace.
[TEST] simplified unicast bw comp test

also fixed unchecked warning in CompositeTestCluster
Documented the query cache module

Related to #7161 and #7167
[TEST] Assert that put mappings requests are acked in GeoMappingTests.
[TEST] fixed unicast bw comp test configuration

The second internal node, when present, wasn't able to join the existing cluster due ti misconfigured unicast hosts, thus it would form its own cluster.
Internal: fixed typo in NodeService s/disovery/discovery
REST spec: Added missing query_cache param to clear_cache, nodes.stats and indices.stats

Relates to #7167 and #7161
Test: Trimmed trailing whitespace to make valid YAML
Tidied up the filters agg docs and added a coming[] tag
[DOCS] fixed title for filters aggregation documentation
[DOCS] Remove the section about codecs.

This documentation was dangerous because it felt like it was possible to gain
substantial performance by just switching the codec of the index.

However, non-default codecs are dangerous to use since they are not supported
in terms of backward compatibility, and most improvements that they bring have
been folded into the default codec anyway (for example, the default codec
"pulses" postings lists that contain a single document).
Java api: remove operationThreaded setter from ExplainRequestBuilder, already available in base class SingleShardOperationRequestBuilder

It also didn't follow the setter convention that we adopted for request builders.
Fixed also javadocs warning caused byt missing descriptions for tag.

Closes #7186