parallels: add support of network interfaces to parallelsDomainDefineXML

parallels: add support of network interfaces to parallelsDomainDefineXML

Allow changing network interfaces in domain configuration.

ifname is used as iterface identifier: if there is interface
with some ifname in old config and there are no interfaces with
such name in the new config - issue prlctl command to delete
the network interface. And vice versa - if interface with
some ifname exists only in new config - issue prlctl command
to create it.

Signed-off-by: Dmitry Guryanov <dguryanov@parallels.com>