Add support for SPICE consoles

While in theory both VNC and SPICE can be enabled at the same
time, this is not expected to be common. Thus, rather than
adding a 'SPICE console' tab, this renames the existing
'VNC console' tab to simply be 'Console'. This tab is setup
to prefer exposing a VNC console, but if that is not enabled,
then expose the SPICE console. The reason for this order is
that the noVNC widget has had much more testing than the
current spice-html5 widget. Thus if both VNC & SPICE are
enabled, VNC is likely a more reliable choice at this point
in time.

Blueprint: libvirt-spice
Change-Id: If3d3769fe8e29c5930ac8b42d841c92182c4be72
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>