Merge branch 'flake8' of https://github.com/josephfrazier/thefuck into josephfrazier-flake8

# Conflicts:
#	thefuck/system/unix.py
#	thefuck/system/win32.py

README.md

@@ -388,6 +388,12 @@ pip install -r requirements.txt
 python setup.py develop
 ```
 
+Run code style checks:
+
+```bash
+flake8
+```
+
 Run unit tests:
 
 ```bash