CLOUDSTACK-4442: Source NAT not applied when network starts up

ensure on network implement/restart/shutdown an ip assoc is sent so that
source nat ip is associated with source nat service provider.
CLOUDSTACK-4115 : Encrypt password in cluster_details table. This fix is to handle upgrades from versions earlier than 3.0.5 and 4.0. Upgrade was not handled when the cluster_details password encryption was introduced.