Fix F401 flake8 warning (x88 / 116).

This change is mostly autogenerated with:

    $ python -m autoflake --in-place --recursive --remove-all-unused-imports --ignore-init-module-imports examples templates transformers utils hubconf.py setup.py

I made minor changes in the generated diff.

templates/adding_a_new_model/configuration_xxx.py

@@ -18,8 +18,6 @@ from __future__ import absolute_import, division, print_function, unicode_litera
 
 import logging
 
-import six
-
 from .configuration_utils import PretrainedConfig
 
 

templates/adding_a_new_model/modeling_tf_xxx.py

@@ -21,10 +21,8 @@
 
 from __future__ import absolute_import, division, print_function, unicode_literals
 
-import itertools
 import logging
 
-import numpy as np
 import tensorflow as tf
 
 from .configuration_xxx import XxxConfig

templates/adding_a_new_model/modeling_xxx.py

@@ -20,7 +20,6 @@
 
 from __future__ import absolute_import, division, print_function, unicode_literals
 
-import itertools
 import logging
 import os
 
@@ -30,7 +29,7 @@ from torch.nn import CrossEntropyLoss, MSELoss
 
 from .configuration_xxx import XxxConfig
 from .file_utils import add_start_docstrings
-from .modeling_utils import PreTrainedModel, prune_linear_layer
+from .modeling_utils import PreTrainedModel
 
 
 logger = logging.getLogger(__name__)

templates/adding_a_new_model/tests/modeling_tf_xxx_test.py

@@ -24,7 +24,6 @@ from .utils import CACHE_DIR, require_tf, slow
 
 
 if is_tf_available():
-    import tensorflow as tf
     from transformers.modeling_tf_xxx import (
         TFXxxModel,
         TFXxxForMaskedLM,

templates/adding_a_new_model/tokenization_xxx.py

@@ -19,7 +19,6 @@ from __future__ import absolute_import, division, print_function, unicode_litera
 import collections
 import logging
 import os
-import unicodedata
 from io import open
 
 from .tokenization_utils import PreTrainedTokenizer