Configure vim with Python PEP8 check

1. install pep8 for Python

sudo pip install  pep8

2.  Download the PEP8.vim plugin from http://www.vim.org/scripts/script.php?script_id=2914

1. Put the plugin to ~/.vim/ftplugin/python/pep8.vim

4.  add the following line to ~/.vimrc

source ~/.vim/ftplugin/python/pep8.vim