Selectable message-type options in device configs

[AaronLionsheep]

Starting in 0.2.4, the plugin examines all triggers and monitors for the current message types that triggers will produce. The device ConfigUI's should be able to generate a selectable list of message types rather then forcing the user to type them manually.

• When a single message type exists for a broker, it should automatically be the selection option after the broker device is chosen in the config.
• Message types should be shown based on which broker device is selected