Disable pretty on FileSystemSink due performance reasons

Author: SYNchroACK

stix2/datastore/filesystem.py

@@ -585,7 +585,7 @@ def _check_path_and_write(self, stix_obj, encoding='utf-8'):
             raise DataSourceError("Attempted to overwrite file (!) at: {}".format(file_path))
 
         with io.open(file_path, mode='w', encoding=encoding) as f:
-            fp_serialize(stix_obj, f, pretty=True, encoding=encoding, ensure_ascii=False)
+            fp_serialize(stix_obj, f, pretty=False, encoding=encoding, ensure_ascii=False)
 
     def add(self, stix_data=None, version=None):
         """Add STIX objects to file directory.