Update pep8 from 1.7.0 to 1.7.1

Author: pyup-bot

requirements/development.txt

@@ -5,7 +5,7 @@ watchdog==0.8.3
 cryptography==2.0.3
 PyYAML==3.12
 coverage==4.4.1
-pep8==1.7.0
+pep8==1.7.1
 pylint==1.7.4
 flake8==3.4.1
 pyflakes==1.6.0