Added submodule vim-flake8

.gitmodules

@@ -19,3 +19,6 @@
 [submodule "vim/vim/bundle/vim-colors-solarized"]
 	path = vim/vim/bundle/vim-colors-solarized
 	url = git://github.com/altercation/vim-colors-solarized.git
+[submodule "vim/vim/bundle/vim-flake8"]
+	path = vim/vim/bundle/vim-flake8
+	url = git://github.com/nvie/vim-flake8.git