VNC Token Validation

Force console auth service to flush all tokens
associated with an instance when it is deleted.
This will fix a bug where the console for the
wrong instance can be connected to via the console
if the correct circumstances occur. This change also
makes a call to veriry vnc console tokens when a
user attempts to connect to a console. This ensures
the user is connecting to the correct console.

bug 1125378
Change-Id: I0d83ec6c4dbfef1af912a200ee15f8052f72da96
Merge "VNC Token Validation" into stable/folsom