libvirt-lxc: rename libvirt_template.go to libvirt_lxc_template.go

Renaming libvirt_template.go to libvirt_lxc_template.go because  there
will also be a libvirt_network_template.go.
libvirt-lxc: create libvirt network

Use libvirt to create a virtual network.  Libvirt will now create and
configure the docker0 bridge interface.