Remove special case for Markdown files

We can treat them using Pandoc just fine.

Author: nickcharlton

vimrc

@@ -126,7 +126,6 @@ augroup vimrcEx
 
   " Set syntax highlighting for specific file types
   autocmd BufNewFile,BufRead *.prawn,Brewfile set filetype=ruby
-  autocmd BufRead,BufNewFile *.md set filetype=markdown
   autocmd BufRead,BufNewFile .{jscs,jshint,eslint}rc set filetype=json
   autocmd FileType text,markdown,mkd,pandoc call lexical#init()
 augroup END