modules/smartos_vmadm : add init(**kwargs)

We can now create (and launch) a Zone (OS virt) by passing correct
arguments/values to the virt.init function.

Example :

    salt * virt.init \
        image_uuid='9eac5c0c-a941-11e2-a7dc-57a6b041988f' \
        alias='test' \
        hostname='www.domain.com' quota=2 max_physical_memory=256 \
        nic_tag='admin' ip='192.168.0.95' netmask='255.255.255.0' \
        gateway='192.168.20.1'