Create protobuf message definitions for techprofile template, techprofile instance and resource instance

Create protobuf message definitions for techprofile template, techprofile instance and resource instance.

Earlier the definitions were maintained as some internal structures within techprofile module and the standard json marshal was used to json-ify the structure and store on etcd. The data from etcd was again unmarshalled and read back to internal structures for processing.

Using protobuf messages allows for better tech profile message passing across different components in the voltha stack as opposed to using some internal structures. Also gives the additional benefits of protobuf optimal encoding/decoding , versioning, extensibility, backward compatibility etc.