Fix vnc docs: novaclient now supports vnc consoles.
Fix vnc docs: novaclient now supports vnc consoles.

 * novaclient now supports retrieval of vnc consoles, so remove
   reference to outdated branch.

Change-Id: Ifb8d7e6d2e15d3674fd32f074d1a92e5035ed941

n0ano/gantt,n0ano/gantt