[python] removed unused pylint directives (#2466)

examples/python-guide/advanced_example.py

 # coding: utf-8
-# pylint: disable = invalid-name, C0111
 import json
 import lightgbm as lgb
 import pandas as pd

examples/python-guide/logistic_regression.py

 # coding: utf-8
-# pylint: disable = invalid-name, C0111
 """Comparison of `binary` and `xentropy` objectives.
 
 BLUF: The `xentropy` objective does logistic regression and generalizes

examples/python-guide/plot_example.py

 # coding: utf-8
-# pylint: disable = invalid-name, C0111
 import lightgbm as lgb
 import pandas as pd
 

examples/python-guide/simple_example.py

 # coding: utf-8
-# pylint: disable = invalid-name, C0111
 import lightgbm as lgb
 import pandas as pd
 from sklearn.metrics import mean_squared_error

examples/python-guide/sklearn_example.py

 # coding: utf-8
-# pylint: disable = invalid-name, C0111
 import numpy as np
 import pandas as pd
 import lightgbm as lgb

python-package/lightgbm/basic.py

 # coding: utf-8
-# pylint: disable = invalid-name, C0111, C0301
-# pylint: disable = R0912, R0913, R0914, W0105, W0201, W0212
 """Wrapper for C API of LightGBM."""
 from __future__ import absolute_import
 

python-package/lightgbm/callback.py

 # coding: utf-8
-# pylint: disable = invalid-name, W0105, C0301
 """Callbacks library."""
 from __future__ import absolute_import
 

python-package/lightgbm/compat.py

 # coding: utf-8
-# pylint: disable = C0103
 """Compatibility library."""
 from __future__ import absolute_import
 

python-package/lightgbm/engine.py

 # coding: utf-8
-# pylint: disable = invalid-name, W0105
 """Library with training routines of LightGBM."""
 from __future__ import absolute_import
 

python-package/lightgbm/plotting.py

 # coding: utf-8
-# pylint: disable = C0103
 """Plotting library."""
 from __future__ import absolute_import, division
 

python-package/lightgbm/sklearn.py

 # coding: utf-8
-# pylint: disable = invalid-name, W0105, C0111, C0301
 """Scikit-learn wrapper interface for LightGBM."""
 from __future__ import absolute_import
 

python-package/setup.py

 # coding: utf-8
-# pylint: disable=invalid-name, exec-used, C0111
 """Setup lightgbm package."""
 from __future__ import absolute_import
 

tests/c_api_test/test_.py

 # coding: utf-8
-# pylint: skip-file
 import ctypes
 import os
 import sys

tests/python_package_test/test_basic.py

 # coding: utf-8
-# pylint: skip-file
 import os
 import tempfile
 import unittest

tests/python_package_test/test_consistency.py

 # coding: utf-8
-# pylint: skip-file
 import os
 import unittest
 

tests/python_package_test/test_engine.py

 # coding: utf-8
-# pylint: skip-file
 import copy
 import itertools
 import math

tests/python_package_test/test_plotting.py

 # coding: utf-8
-# pylint: skip-file
 import unittest
 
 import lightgbm as lgb

tests/python_package_test/test_sklearn.py

 # coding: utf-8
-# pylint: skip-file
 import itertools
 import joblib
 import math