* CloudWatch: Datasource improvements

* Add statistic as template variale

* Add wildcard to list of values

* Template variable intercept dimension key

* Return row specific errors when transformation error occured

* Add meta feedback

* Make it possible to retrieve values without known metrics

* Add curated dashboard for EC2

* Fix broken tests

* Use correct dashboard name

* Display alert in case multi template var is being used for some certain props in the cloudwatch query

* Minor fixes after feedback

* Update dashboard json

* Update snapshot test

* Make sure region default is intercepted in cloudwatch link

* Update dashboards

* Include ec2 dashboard in ds

* Do not include ec2 dashboard in beta1

* Display actual region