Mova nova configuration initialization

* Move shared volume configuration from stack.sh to stackrc
* Move Nova network and vnc/spice configuration settings from stack.sh
  into lib/nova
* Rename NET_MAN to NETOWRK_MANAGER to match nova.conf attribute name

Change-Id: I9bd2955def553499aa832eda1f0959afe494206a
Merge "Mova nova configuration initialization"