title: Retrieve optional query variables with gorilla mux?
body: <p>I'm writing a handler that can take either POST or GET. As such, I want the option of being able to say:</p>
  
  <pre><code>http://host/query?parm1=value&amp;parm2=value
  </code></pre>
  
  <p>I was assuming that Gorilla mux would then give me:</p>
  
  <pre><code>{
      "parm1": "value",
      "parm2": "value
  }
  </code></pre>
  
  <p>but <code>mux.Vars(r)</code> is empty. I'm aware that using <code>.Query("key", "value"</code> will make the parameters mandatory, which isn't what I want. What am I missing?</p>