Logging

Add logging that could be useful for debugging

❯ flake8 -v
local configuration: in /Users/marca/dev/git-repos/flake8
DEBUG:flake8.engine:before adding EXTRA_EXCLUDE: options.exclude = ['.git', '.tox', 'dist', 'docs', '*egg']
DEBUG:flake8.engine:after adding EXTRA_EXCLUDE: options.exclude = ['.git', '.tox', 'dist', 'docs', '*egg', '.tox']
directory .
checking ./run_tests.py
directory ./.eggs
directory ./bin
checking ./setup.py
directory ./eggs
checking ./bin/git-patch-to-hg-export.py
directory ./flake8
checking ./flake8/__init__.py
checking ./flake8/__main__.py
checking ./flake8/_pyflakes.py
checking ./flake8/engine.py
checking ./flake8/hooks.py
checking ./flake8/main.py
checking ./flake8/reporter.py
checking ./flake8/run.py
checking ./flake8/util.py
directory ./flake8/__pycache__
directory ./flake8/tests
checking ./flake8/tests/__init__.py
checking ./flake8/tests/test_engine.py
checking ./flake8/tests/test_integration.py
directory ./flake8/tests/__pycache__
directory ./flake8.egg-info
./flake8/engine.py:18:80: E501 line too long (127 > 79 characters)

❯ flake8
./flake8/engine.py:18:80: E501 line too long (127 > 79 characters)

Note that the E501 message above is not a real problem; it's the result of me putting in an error on purpose so that the output looks more realistic.