Upgrade flake8 to version 2.4.1
Upgrade flake8 to version 2.4.1

brian-yang/mozillians,brian-yang/mozillians,safwanrahman/mozillians,johngian/mozillians,chirilo/mozillians,johngian/mozillians,akatsoulas/mozillians,anistark/mozillians,anistark/mozillians,akatsoulas/mozillians,fxa90id/mozillians,akatsoulas/mozillians,fxa90id/mozillians,mozilla/mozillians,fxa90id/mozillians,mozilla/mozillians,chirilo/mozillians,chirilo/mozillians,mozilla/mozillians,johngian/mozillians,safwanrahman/mozillians,brian-yang/mozillians,akatsoulas/mozillians,anistark/mozillians,johngian/mozillians,brian-yang/mozillians,safwanrahman/mozillians,chirilo/mozillians,anistark/mozillians,safwanrahman/mozillians,fxa90id/mozillians,mozilla/mozillians