adjust input data for ActionsByTimeOfDay chart

[hagoptaminian]

In this app, the chart ActionsByTimeOfDay plots 'time of day' (x-axis) and 'number of actions' (y-axis). Currently, the 'time of day' input is derived from an action's createdAt tag, which is an auto-generated timestamp logged by our server, corresponding to the CET time the action was made. However, this doesn't mean the action was actually performed at that time: If the action was made in (say) the EST timezone, it was made -06:00 hours before the createdAt timestamp.

This can be fixed. Each action object has (e.g.):

"geolocation": { "country": "CH", region: "ZH", "timezone": "Europe/Zurich", "city": "Zurich", ...}

which we can use to derive the correct time the action was made.