Delete STORAGEDIR folders when services are removed

Hello, currently when a service is removed (Remove d-bus method) some of its properties are cleared but its folder and files in STORAGEDIR are not deleted. This patch removes such data. Immutable services have a .config file in STORAGEDIR, and if they have been connected at least once they also have the same folder of mutable services: the Remove method will delete the folder and force a re-provision of the service: this will act as a reset of the service to its default. Regards, Marco Maniezzo