Elasticsearch: No option for 'nested' type bucket aggregation to deal with nested fields

[arcolife]

Currently it's not possible to do bucket aggregation for nested type docs, even if PR #4527 would add nested type autocomplete feature. The query editor mode was removed, and even if it were there, grafana currently doesn't know how to deal with nested bucketed aggregation results. Would be nice to have this sorted out too.
Cheers!

• What grafana version are you using?
  3.0.0 (latest from master branch)
• What datasource are you using?
  elasticsearch
• What OS are you running grafana on?
  fedora 23

[arcolife]

PR #4694 takes care of this.

WIP
Have to make changes to add:

1. autocomplete to the "nested query" field
2. Unit tests for all the additions..

• I've also included changes from PR add nested support to fieldname autocomplete; fixes #4526 Also: #4527 in this one (so takes care of [Feature Request] getFields() doesn't support nested mapping; fails if current date's index is absent #4526 ..Maybe we could use github's new PR squash to merge them.

A working example: