Added PortForwardingServiceProvider, StaticNatServiceProvider, rename
PasswordServiceProvider to UserDataServiceProvider(may rename to a better name
later).
Add related function for service providers.
-Bringing add/delete/list of all external network devices under one unified API's (addNetworkDevice, deleteNetworkDevice, listNetworkDevice)
-Refactoring External network manager to work from both sets of API's add/delete/list NetworkDevice and add/delete/list External Firewall/LoadBalancer
Sheng Yang
Murali Reddy