Fix #59 by removing direct dependency on pyflakes

setup.py

diff --git a/setup.py b/setup.py
index 0b3ed31..4e04461 100644
--- a/setup.py
+++ b/setup.py
@@ -30,7 +30,6 @@
         'flake8',
         'argparse',
         'autopep8>=1.1',
-        'pyflakes',
         'pyyaml',
         'simplejson',
     ],