Set preferences.

        :return:

def _set_preferences(self, node):
        '''
        Set preferences.

        :return:
        '''
        pref = etree.SubElement(node, 'preferences')
        pacman = etree.SubElement(pref, 'packagemanager')
        pacman.text = self._get_package_manager()
        p_version = etree.SubElement(pref, 'version')
        p_version.text = '0.0.1'
        p_type = etree.SubElement(pref, 'type')
        p_type.set('image', 'vmx')

        for disk_id, disk_data in self._data.system.get('disks', {}).items():
            if disk_id.startswith('/dev'):
                p_type.set('filesystem', disk_data.get('type') or 'ext3')
                break

        p_type.set('installiso', 'true')
        p_type.set('boot', "vmxboot/suse-leap42.1")
        p_type.set('format', self.format)
        p_type.set('bootloader', 'grub2')
        p_type.set('timezone', __salt__['timezone.get_zone']())
        p_type.set('hwclock', __salt__['timezone.get_hwclock']())

        return pref