ADStxt.py: include reference file in error log message

[ehenneken]

When an exception is generated during the call of get_references in class PairsTXTtoREFs(ADStxtToREFs) of the ADStxt.py parser, this exception is caught, however the error message does not contain enough specifics (i.e. the reference file that generated the problem)

        except Exception as e:
            logger.error('Exception: %s' % (str(e)))
            return []

The error message minimally needs to contain the file name of the reference file being processed.