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

Service		unique name
Interface	net.connman.iwd.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.

		string RequestPassphrase(object network)

			This method gets called when trying to connect to
			a network and passphrase is required.

			Possible Errors: net.connman.iwd.Agent.Error.Canceled

		void Cancel(string reason)

			This method gets called to indicate that the agent
			request failed before a reply was returned.  The
			argument will indicate why the request is being
			cancelled and may be "out-of-range", "user-canceled",
			"timed-out" or "shutdown".

Examples	Requesting a passphrase for WPA2 network

			RequestPassphrase("/network1")
			==> "secret123"