This commit allows for a user configurable VNC bind IP to be used for
QEMU.
By default this will be 127.0.0.1, alternatively, a user can use
0.0.0.0 which will bind to all interfaces.
This pull request should satisfy concerns of #3570 and #3559. It is
also in-line with the functionality provided by #3566 and #3565
Signed-off-by: Ian Duffy <ian@ianduffy.ie>