hugepages vdsm hook
===================
hook is getting hugepages=512 and will preserve 512
huge pages

hook is doing the following:
add pages: sysctl vm.nr_hugepages=516
add the following xml in domain\devices:
    <memoryBacking>
        <hugepages/>
    </memoryBacking>

NOTE:
hugepages must! be mounted prior to libvirt start up,
ie:
# mount -t hugetlbfs hugetlbfs /dev/hugepages
# initctl restart libvirtd

Syntax:
hugepages=512
