gbcbd_get_JSON_fct      Function for switching functions depending on
                        using cache or not
gbcbd_get_default_cache_folder
                        Returns default cache folder
gbcbd_get_series        Imports time series data from BCB-SGS System
                        (Banco Central do Brasil, sistema de series
                        temporais)
gbcbd_get_single_series
                        Gets a single series from BCB-SGS (internal
                        use)
gbcbd_message           Custom function for printing messages
gbcbd_test_internet     Tests for an internet conection
