* Elasticsearch - Term aggregation limit fix  (should fix #7112)

* Elasticsearch - Term aggregation limit fix

Add a note about the `go get` warning that the user sees when following the setup instructions.

Added commonly used kilo-prefixed energy units

Kilovolt-ampere reactive (kvar)
Kilovolt (kV)
Kiloampere (kA)

Change all bool queries to use 'filter' clause instead of 'must' for
better performance

Documentation calls for `annotationQuery` but the [example](https://github.com/grafana/simple-json-datasource/blob/205cf4cfbce95cd455da97c7972b64538cc80ab3/src/datasource.js#L41) uses the method name `annotationQuery`

Use configuration variable "show_alerting_ui" to show/hide alerting UI

When a tag doesn't have a value it was showing a empty 'bubble'.
If value has several values separated by commas, make a 'bubble' for
each one.

closes #7268

Some email providers does not accept localhost
in the HELO message. So we set it to hostname
instead. Our hope is that should be enough for
those providers who does not accept localhost.

closes #7223

closes #7035
ref #7257