WIP: DBus interface changes for tree data model

Changed the DBUS introspection file for tree data model changes in rhosydd. Major changes are as follows

1. zone is no more required
2. meta data is changed from (uu) to a{sv} i.e. array of key - value pairs, where each pair represents certian info specific to the attribute. e.g. Metadata for vehicle speed reads as follows datatype: "uint16" unit: "km/h" min: 0 max: 300 description: "The vehicle speed, as measured by the drivetrain."
3. For GetAllMetadata or GetAllAttributes a new input named 'node_path' is added. This is the path to the targeted node / branch mastering the required attributes.