All VNC-specific configuration bits are moved from nova-api-base to
nova-compute and the new nova-novncproxy and nova-consoleauth
containers. The compose specification has been updated to reflect this.
A future patch will make the desired backend configurable (spice/vnc).
Change-Id: I8b64abf125fd1ecd7d3463515e3717dd9bd60420
Blueprint: novnc-container