Aggregations: Only return aggregations on the first page when scrolling.

Aggregations are collection-wide statistics so they would always be the same.
In order to save CPU/bandwidth, we can just return them on the first page.

Same as #1642 but for aggregations.
Aggregations: Forbid usage of aggregations in conjunction with search_type=SCAN.

Aggregations are collection-wide statistics, which is incompatible with the
collection mode of search_type=SCAN since it doesn't collect all matches on
calls to the search API.

Close #7429
Packaging: Add default oracle jdk 7 (x64) path in debian init script

On Debian amd64, oracle jdk .deb packages made using make-jpkg (from
java-package) default to /usr/lib/jvm/jdk-7-oracle-x64.

Closes #7312
Internal: remove unused constructor and adjust methods visibility in DelegatingActionListener
Java api: remove needless copy constructor from DeleteIndexedScriptRequest
Internal: fix members visibility, remove unused constant and needless try catch in indexed scripts transport actions
Java api: change base class for GetIndexedScriptRequest and improve its javadocs

`GetIndexedScriptRequest` now extends `ActionRequest` instead of `SingleShardOperationRequest`, as the index field that was provided with the previous base class is not needed (hardcoded).

Closes #7553
_boost: Fix "index" setting

Serialization if "index" setting for boost did not work since
the serialization was just true/false instead of valid options
"no"/"not_analyzed"/"analyzed".