title: flake8 doesn't report mixed-case function names
body: <p>I created a short script called <code>test_pep8.py</code> containing the following:</p>
  
  <pre><code>def myFunc():
      return None
  </code></pre>
  
  <p>I would expect flake8 to produce a warning about mixed case function names. But, flake8 reports no warnings:</p>
  
  <pre><code>&gt; flake8 --verbose test_pep8.py
  checking test_pep8.py
  </code></pre>
  
  <p>I then ran pep8 directly on the file and got the same result:</p>
  
  <pre><code>import pep8
  checker = pep8.Checker('test_pep8.py')
  checker.check_all()
  &gt; 0
  </code></pre>
  
  <p>Checking out the pep8 library, I noticed this set of default ignores:</p>
  
  <pre><code>DEFAULT_IGNORE = 'E121,E123,E126,E226,E24,E704'
  </code></pre>
  
  <p>But, incorrect function naming doesn't appear to be listed.</p>
  
  <p>Here's my flake8 version info:</p>
  
  <pre><code>&gt; flake8 --version
  2.3.0 (pep8: 1.6.2, pyflakes: 0.8.1, mccabe: 0.3) CPython 2.6.6 on Linux
  </code></pre>
  
  <p>Anyone know why flake8 is not reporting this pep8 violation? Thanks!</p>
  
  <p>EDIT:
  Just spotted this module: <a href="https://pypi.python.org/pypi/pep8-naming" rel="noreferrer">https://pypi.python.org/pypi/pep8-naming</a>
  Is pep8 naming now enforced by a different library? I seem to remember pep8 covering that before, but I could be mistaken.</p>
  
  <p>pep8-naming does seem to be the solution:</p>
  
  <pre><code>&gt; flake8 --verbose test_pep8.py
  checking test_pep8.py
  test_pep8.py:5:5: N802 function name should be lowercase
  </code></pre>