Update feed to communicate important updates and bugs

[matthme]

With the broken auto-updates on Windows and macOS in versions 0.11.9 and 0.11.10 I realized that - given that we start having users - it's important that we have a way to communicate important updates or bugs with workarounds to our users. This PR is an attempt for a simple solution for this. It fetches notifications from the news.json file from the we repository and displays them on the main page in Moss.