Sort and truncate pipeline aggregation

[colings86]

This would be a parent pipeline aggregation which would take the following option:

• Sort - a bucketsPath that defines the aggregation(s) in each bucket to use to sort the buckets in the parent aggregation. If this is not provided no sorting is done on the buckets
• Offset - all buckets before this index in the sorted buckets list will be removed. Defaults to 0 (i.e. don't remove any buckets from the beginning of the list)
• Size - all buckets after offset + size index in the sorted buckets list will be removed. Defaults to buckets.size() (i.e. don't remove any buckets from the end of the list)

[eskibars]

+1

[taowen]

+1

[davyfeng]

+1