Always use the original file format when downloading files.

Otherwise, the files will not have the correct hashes, as dataverse replaces, e.g., csv or R table files with its own tabular data format.

Closes #307.

datalad_dataverse/dataset.py

@@ -171,7 +171,7 @@ def download_file(self, fid: int, path: Path):
         # https://github.com/gdcc/pyDataverse/issues/49
         # the code below is nevertheless readied for such a
         # scenario
-        response = self.data_access_api.get_datafile(fid)
+        response = self.data_access_api.get_datafile(fid, data_format="original")
         # http error handling
         response.raise_for_status()
         with path.open("wb") as f: