Add support for symbol based serialization/RPC

Currently the remote service admin and pubsub are based on the use of dfi and descriptors. Another option could be to support the de/serialization and RPC using predefined function signatures.

Using the extender pattern these function can be found and used without polluting the types/services with serialization/RPC code and make it possible to support a wide range of existing serialization/rpc techniques.

For example a service with the name "HelloWord" could have a bundle entry 'META-INF/services/HelloWorld.rpc_info' entry containing a simple properties files with - atleast- the entires "create_proxy" and "create_endpoint". These refer to symbols in the shared libraries of the bundle with predefined signatures.

More design details are needed before this can be implemented. Also a initial tech. should be chosen (e.g. RPC).

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Original creation date: 09/Apr/2018
Reporter: @pnoltes