HistoryLogger - Unify Output for Backends
At the moment the history output of a training is based on backend to make use of the given information (e.g. keras --> history object) To unify the output across the backends in src/utils/history_logger method _unify_back_history should be changed to the required variables as input and making the file output based on them. Each Backend has to inherite from HistoryLogger (see KerasBackendSL for an example) and call _unify_back_history with the specified parameters read from the given output of the backend.