Feature: Pause Data-Refresh if in Background

[ansibleguy]

Scope

Frontend (User Interface)

Description

As described in #30 the current data-fetching is far from being perfect.
It does not make sense to have the data fetched if AW is in the background/on an inactive tab.
We could pause the fetching until it has become active again.
See: https://developer.mozilla.org/en-US/docs/Web/API/Page_Visibility_API