Fix typo with vncproxy_host for ::nova::compute

This commit fixes an issue where nova::compute was defaulting to
127.0.0.1:6080 even though the public_ipaddress was passed.

Change-Id: Ibb5247d715247a8a2c519a08c3af1a8ff79304a2
Signed-off-by: Paul Belanger <paul.belanger@polybeacon.com>