Added todo about parameterizing schema generation

It should be possible to chose between a normalized and a not normalized schema in the future.

performance_test.py

@@ -89,6 +89,8 @@ def get_process_memory_usage():
 def get_field_names_and_schema():
   '''Returns the array's dtype and its field names.'''
   field_names = ['f%s' % number if not number == 13 else 'quantity' for number in range(23)]
+  
+  # TODO: parameterize to get normalize or not normalized schema
   array_schema = np.dtype({
     'names' : field_names,
     'formats': map(