This commit moves template support out of the Search API to its own dedicated Search Template API in the lang-mustache module. It provides a new SearchTemplateAction that can be used to render templates before it gets delegated to the usual Search API. The current REST endpoint are identical, but the Render Search Template endpoint now uses the same Search Template API with a new "simulate" option. When this option is enabled, the Search Template API only renders template and returns immediatly, without executing the search.
Closes#17906
In Elasticsearch 5.0.0, by default unquoted field names in JSON will be
rejected. This can cause issues, however, for documents that were
already indexed with unquoted field names. To alleviate this, a system
property has been added that can be enabled so migration can occur.
This system property will be removed in Elasticsearch 6.0.0
Resolves#17674
The available memory metric was always set to `0` since 2.0.beta1 (bug). was left behind but never set. Turns out the section wasn't that useful, as it would only output the total memory available throughout all nodes in the cluster. We decided to remove the section then.
