Add a get_spice_console method to nova.virt.ComputeDriver API

To mirror the existing get_vnc_console method, add a new
get_spice_console method to nova.virt.ComputeDriver API.

No attempt is made to wire this up to the RPC API, since at
this time there is no equivalent of novnc or xvpvncproxy to
use with SPICE.

Blueprint: libvirt-spice
Change-Id: I4cf12074b240d6882e46a81783cf20a3d97d4b2a
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Merge "Add a get_spice_console method to nova.virt.ComputeDriver API"