title: Formatting date in specified timezone using Moment Timezone
body: <p>If you change time zone to (UTC-07:00) Mountain Time and run the code below you can see the problem that I'm talking about.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>var a = moment('2009-11-01T06:00:00Z').tz('US/Mountain').format();
  var b = moment('2009-11-01T06:00:00Z').tz('US/Mountain').format('YYYY-MM-DD HH:mm');
  var c = moment('2009-10-31T23:00:00-07:00').format('YYYY-MM-DD HH:mm');
  
  document.getElementById("a").innerHTML = "#1: " + a;
  document.getElementById("b").innerHTML = "#2: " + b;
  document.getElementById("c").innerHTML = "#3: " + c;</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="http://momentjs.com/downloads/moment.min.js"&gt;&lt;/script&gt;
  &lt;script src="http://momentjs.com/downloads/moment-timezone-with-data-2010-2020.min.js"&gt;&lt;/script&gt;
  &lt;div id="a"&gt;&lt;/div&gt;
  &lt;div id="b"&gt;&lt;/div&gt;
  &lt;div id="c"&gt;&lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>The date offset produced by running the code (#1) above is correct. However, shouldn't formatting it change the value to "2009-11-01 00:00" (#3) instead of "2009-10-31 23:00" (#2)?</p>
  
  <p>It seems like the formatter just strips the offset instead of taking it into account when producing the formatted date. Is this a bug or am I doing something wrong here?</p>