Include blueoil/converter and tests/converter in pep8 test

[tfujiwar]

In pep8 tests, blueoil/converter and tests/converter is excluded. If we include those directories, there are about 430 errors but about 330 of them are about F405 and easy to fix.

./blueoil/converter/core/operators.py:34:20: F405 'List' may be undefined, or defined from star imports: .data_types

There is another error about star imports. We can fix this error by using import data_types as dt.

./blueoil/converter/core/operators.py:28:1: F403 'from .data_types import *' used; unable to detect undefined names

The remaining 100 errors are about formatting, unused modules, unused variables, etc.