* Make the Fork Awesome image provider URL a property and change its value
if the Plasmoid's theme changes to cause Qt Quick to redraw images
* Turn caching of Image objects off so Qt Quick actually fetches the images
again from the image provider
* Change the URL only back after returning to the event loop; otherwise Qt
Quick apparently does not react to the property change
* See https://github.com/Martchus/syncthingtray/issues/126
This should avoid:
```
file:///usr/share/plasma/plasmoids/martchus.syncthingplasmoid-git/contents/ui/main.qml:13:34: QML FullRepresentation: Binding loop detected for property "implicitWidth"
…
qml: PlasmaExtras.ScrollArea is deprecated. Use PlasmaComponents3.ScrollView instead.
…
file:///usr/share/plasma/plasmoids/martchus.syncthingplasmoid-git/contents/ui/TabButton.qml:27:13: Unable to assign [undefined] to QFont
…
file:///usr/share/plasma/plasmoids/martchus.syncthingplasmoid-git/contents/ui/ToolButton.qml:23:13: Unable to assign [undefined] to QFont
```
Martchus