Support GPU data

[solazs]

The plasmoid is awesome, but GPU temperature would make it more complete.

This is mentioned in #9, too.

For proprietary NVIDIA drivers the nvidia-smi command can provide all kinds of information.
Unfortunately I haven't been able to add the NVIDIA sensors to the sensors output.

[Estacado7706]

It's rather simple. Just add another DataSource to the ui and edit the model to your likings.
A source for NVidia cards with the respective driver would be:

PlasmaCore.DataSource {
id: nvidiaSource
engine: "executable"
interval: 1000

    property string nvSource: 'nvidia-smi --query-gpu=temperature.gpu --format=csv,noheader'

    [insert further handling of the source]

}