add tree of directories to vim path

.vimrc

python << END_PATH
import os
import vim 
walker = os.walk(os.getcwd())
dir_list = ['.']
for root, dirs, paths in walker:
    dir_list += map(lambda d: os.path.join(root, d), dirs)
vim.command('set path=%s' % ','.join(dir_list))
END_PATH