Agent hierarchy
===============

Service		unique name
Interface	org.moblin.connman.Agent
Object path	freely definable

Methods		void Release()

			This method gets called when the service daemon
			unregisters the agent. An agent can use it to do
			cleanup tasks. There is no need to unregister the
			agent, because when this method gets called it has
			already been unregistered.

		void ReportError(object service, string error)

			This method gets called when an error has to be
			reported to the user.

			A special return value can be used to trigger a
			retry of the failed transaction.

			Possible Errors: [service].Error.Retry

		string RequestPassphrase(object service)

			This method gets called when trying to connect to
			a service and a passphrase is missing.

			The return value should be the passphrase string or
			an error indicating that the request got cannceled.

			Possible Errors: [service].Error.Canceled

		void Cancel()

			This method gets called to indicate that the agent
			request failed before a reply was returned.