Bug fixing: resume crashed checking # of predictions

- The checkpoint function did not return a tuple
Bug fixing: resume crashed when checking the completeness of remote predictions
Bug fixing: the field structure used in input data checking was not complete
Bug fixing: remote prediction with one or many models appended test data
Adding replacement=True for ensemble default creation value
Updating version to 0.3.5, test adjust and cleaning
Bug fixing: --model-fields flag was not used in ensemble creation

- Adding model-fields information to ensemble creation
- Adding store flag to tests
Changing check files in tests to match backend tree changes