Add Widget Preview

[niccokunzmann]

It would be nice to see a preview of how the widget will look like when the space is open/closed according to the hackspace chosen.

Below the configuration, it would be nice to see the widget displayed like this:

• current status
• open status
• closed status

Whenever the configuration is changed, I would like to see these images update.

• Also nice below would be a link to a description of how to change the SpaceAPI json so that the image can be changed on the app. Should be this