Cold start issues

[maakuth]

Clean checkout and running execution results in some issues with data sources, namely:

• FingridService's cachedFingridRealtimeResponse fails to update so no price data is visible
• NordpoolspotView.createEstimateDataSeries gets called with empty dataSource, resulting in an exception while executing the view code
• Also there's an error about missing pakastin-2-year.json, but that goes away by refreshing.

To get this up and running for #8 development, I solved these for myself by adding some null checks, but I'm not sure if that fixes the issue in the wrong place. I can publish a branch of those if you think they'd be helpful.

I tried these both on Windows and Linux environments, so at least it is not only an issue in one of them.