title: how to change the default version of node through lastest NVM.
body: <p>I am using latest nvm 0.24.1 .. </p>
  
  <p>I install 3 node. 0.8, 0.10 and latest 0.12. I first make 0.10 as default node using aliast</p>
  
  <pre><code> nvm alias default 0.10
  </code></pre>
  
  <p>Now, I want to change the 0.10 to 0.12 as default. Will anybody tell, how can I change. </p>