userportal: Fix VM Basic item button element IDs

Element IDs for VM Basic item buttons (Run, Shutdown, Suspend)
were not initialized correctly, since item View's add*Button
methods are now called early on, as part of item PresenterWidget
onBind method (setElementId is called later on).

Change-Id: Ie3ec57e493ad3de36e5fa494d4fdc4d3eefbc9da
Signed-off-by: Vojtech Szocs <vszocs@redhat.com>