***Logging**: Moved to structured logging lib, and moved to component specific level filters via config file, closes [#4590](https://github.com/grafana/grafana/issues/4590)
***OpenTSDB**: Support nested template variables in tag_values function, closes [4398](https://github.com/grafana/grafana/issues/4398)
***Datasource**: Pending data source requests are cancelled before new ones are issues (Graphite & Prometheus), closes [5321](https://github.com/grafana/grafana/issues/5321)
## Breaking changes
***Logging** : Changed default logging output format (now structured into message, and key value pairs, with logger key acting as component). You can also no change in config to json log ouput.
