added datasource chooser in outage dashboard

[mfuhrmann]

It's tested with Grafana 6 and 3 ONMS instances.

@indigo423 Can you please test it? Also an update on grafana.org is required.

[indigo423]

For some reasons, I get a "No data sources found" error:

This is what my data sources look like. I tried also to made PostgreSQL default it doesn't change anything.

[mfuhrmann]

I see! And understand why!
PostgreSQL is to generic in my opinion. Since you can have more than OpenNMS PostgreSQL DBs in your Grafana, I've set the datasource filter to
.*OpenNMS.*/.
In my test system I had multiple ONMS PG datasources like PostgreSQL OpenNMS Location 1, PostgreSQL OpenNMS Location 2, PostgreSQL OpenNMS Location 3.

So we should add this information into the board description on grafana.org as well.