Merge pull request #139 from Pablitinho/example_identifiers_file_open_in_read_mode_only

example_identifiers_file is not able to open due a permissions issue.

Author: TjarkMiener

dl1_data_handler/reader.py

@@ -276,7 +276,7 @@ def __init__(
         if example_identifiers_file is None:
             example_identifiers_file = {}
         else:
-            example_identifiers_file = pd.HDFStore(example_identifiers_file)
+            example_identifiers_file = pd.HDFStore(example_identifiers_file, mode='r')
 
         if "/example_identifiers" in list(example_identifiers_file.keys()):
             self.example_identifiers = pd.read_hdf(