add general Widget

[JulianMa]

At the moment, all Widgets are created for a specific use-case. Adding a new service type to the Board, also requires to write a new Widget.
Thats why we should add a general widget. This widget awaits a predefined JSON Structure at the specified URL and can display basic informations.
A JSON Could look like this:

{ 
"title": "Monitoring",
"url": "monitoring-platform.test.local",
"description": "Offer processed in 16 seconds",
"status": "SUCCESS"
}

and result in a Widget like this:

[matthiasbalke]

@r3sist3nt Sounds like a good idea, PRs are very welcome!