compute/hypervisor: refactorize console management

In a previous commit, the way to call nova::compute was not really
optimal. Now it's configuring nova::compute automatically for Spice &
novnc cases.
Also fix the doc for server_proxyclient_address param.

Change-Id: I626601507a55ca60e05c8160176fe4a67e54cb3a
Merge "compute/hypervisor: refactorize console management"