Just like we added the RPC methods, the notification handlers can also
be registered using a function decorator, and we auto-subscribe when
asked for a manifest.
Signed-off-by: Christian Decker <decker.christian@gmail.com>
It's flask inspired with the Plugin instance and decorators to add
methods to the plugin description.
Signed-off-by: Christian Decker <decker.christian@gmail.com>