QNX/RemoteLinux/Madde: Made device test more generic

Any device inheriting from LinuxDevice can now implement
a createDeviceTester() method to return their own
AbstractLinuxDeviceTester that runs when the device wizard
is completed, or when the Test Device button is pressed.

The MaddeDevice implementation of the device actions now completely
matches that of LinuxDevice, so those are removed.

The QNX device check was improved with additional tool checking.

Change-Id: Ie761b7cfc5591238aa2a18a74fe1843fb2cdbeaa
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>
Reviewed-by: Nicolas Arnaud-Cormos <nicolas@kdab.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>