CLOUDSTACK-4762 : Enabling VGPU support for XenServer.
This feature is to enable the GPU-passthrough and vGPU functionality,
with the help of this feature, admins/users will be able to leverage
the GPU graphics unit power by deploying a virtul machine with GPU or
vGPU support or by changing the service offering of an existing VM
at any later point of time. There GPU/vGPU enabled VMs are able to run
graphical applications.
For now, this feature is only supported with XenServer hypervisor but
can be extended to add the support of other hypervisors.