title: vim git gutter realtime update not working
body: <p>I'm trying to configure vim git-gutter in my terminal but I can't seem to enable the realtime functionality. 
  It updates the gutter on save, it want the update to be realtime ( when I exit insert mode )</p>
  
  <p>I added this to my .vimrc</p>
  
  <pre><code>let g:gitgutter_realtime = 0  
  let g:gitgutter_eager = 0
  </code></pre>
  
  <p>I read on the docs that I should set updatetime to something lower, all tough this also doesn't seem to do anything:</p>
  
  <pre><code>set updatetime=250
  </code></pre>
  
  <p>How can I make it work real time ?</p>