add vim-markdown plugin

All our how-to files are in markdown, so this makes sense to install. It's also
kind of late :P

.gitmodules

@@ -67,3 +67,6 @@
 [submodule "vim/bundle/vim-snippets"]
 	path = vim/bundle/vim-snippets
 	url = https://github.com/honza/vim-snippets.git
+[submodule "vim/bundle/vim-markdown"]
+	path = vim/bundle/vim-markdown
+	url = https://github.com/plasticboy/vim-markdown.git

vim/bundle/vim-markdown

@@ -0,0 +1 @@
+Subproject commit 12ec4c1fbf9b99275e138682b1078f7e15c50258

vim/vimrc

@@ -311,6 +311,10 @@ let g:syntastic_auto_jump = 1
 let g:ctrlp_working_path_mode = 'rw'
 
 
+""""""""" Vim Markdown
+let g:vim_markdown_folding_disabled=1
+
+
 """"""""
 "" Functions
 """"""""""""""""""""""""""""""""""""""""""""""""""""""""