Fix and setup linting for python scripts

```
$ python --version
Python 3.5.0+
```

```
$ cd scripts/
flake8 --ignore=E501,E402
./windows_build_module_wheels.py:14:1: F401 'wheel_builder_utils.push_dir' imported but unused
./windows_build_module_wheels.py:17:1: E302 expected 2 blank lines, found 1
./windows_build_module_wheels.py:20:17: E126 continuation line over-indented for hanging indent
./windows_build_module_wheels.py:37:13: F841 local variable 'source_path' is assigned to but never used
./windows_build_module_wheels.py:59:1: E305 expected 2 blank lines after class or function definition, found 1
./windows_build_wheels.py:110:13: E126 continuation line over-indented for hanging indent
./windows_build_wheels.py:220:9: F821 undefined name 'python_executable'
./update_python_version.py:27:5: E128 continuation line under-indented for visual indent
./setup_py_configure.py:112:25: W503 line break before binary operator
./setup_py_configure.py:113:25: W503 line break before binary operator
./setup_py_configure.py:148:9: E303 too many blank lines (2)
./setup_py_configure.py:151:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:152:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:153:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:154:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:155:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:158:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:159:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:160:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:161:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:164:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:167:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:168:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:171:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:172:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:173:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:176:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:177:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:178:13: E128 continuation line under-indented for visual indent
./setup_py_configure.py:217:17: E123 closing bracket does not match indentation of opening bracket's line
./setup_py_configure.py:222:9: E123 closing bracket does not match indentation of opening bracket's line
./setup_py_configure.py:279:9: E123 closing bracket does not match indentation of opening bracket's line
./setup_py_configure.py:285:9: E123 closing bracket does not match indentation of opening bracket's line
./setup_py_configure.py:305:1: E305 expected 2 blank lines after class or function definition, found 1
./internal/windows_build_common.py:11:1: E302 expected 2 blank lines, found 1
```