title: moment.js add doesn't add time
body: <p>when I do </p>
  
  <p>---- edit ----</p>
  
  <pre><code>var someMoment = moment('6:30 PM', ["h:mm A"]);
  </code></pre>
  
  <p>---- end edit ----</p>
  
  <pre><code>someMoment.add(30, 'minutes')  
  </code></pre>
  
  <p>I don't seem to get any result.</p>
  
  <pre><code>console.log(start); -- Moment {_isAMomentObject: true, _i: "6:30 PM", _f: "h:mm A", _isUTC: false, _pf: Object…}
  console.log(start.add(inc, 'minutes')); --Moment {_isAMomentObject: true, _i: "6:30 PM", _f: "h:mm A", _isUTC: false, _pf: Object…}
  </code></pre>
  
  <p>The docs say that add mutates the specified moment, so the above should work but I've also tried</p>
  
  <pre><code>var end = start.add(inc, 'minutes')
  console.log(end); --Moment {_isAMomentObject: true, _i: "6:30 PM", _f: "h:mm A", _isUTC: false, _pf: Object…}
  </code></pre>
  
  <p>what I can do though is this </p>
  
  <pre><code>console.log(start.add(inc, 'minutes').format("h:mm A")); --7:00 PM
  </code></pre>
  
  <p>What I want is to take a moment, add 30 minutes to it and, preferably have a new moment that is 30 minutes ahead, or at least have the initial moment be 30 minutes ahead.  </p>
  
  <p>I know I can take the format out put and put it in a new moment, and I guess I will but this seems kind of broken.</p>
  
  <p>---- edit ----</p>
  
  <p>using moment 2.1</p>
  
  <p>I am getting this from within a method in my app, I haven't isolated it in a jsfiddle or anything, but the method takes a string and a increment.  I guess I'll paste it here</p>
  
  <p>here i'm trying one way but I've also tried using the modified start and cloning the start</p>
  
  <pre><code>var timeIsBetweenStartInc = function(_target:string, _start:string, inc:int){
  var target = moment(_target, ["h:mm A"]);
  var start = moment(_start, ["h:mm A"]);
  console.log(start);
  var end = moment(start).add(inc, 'minutes');
  console.log(end);
  
  return target.isBetween(start, end, 'minutes', '[)');(target, start, end);
  };
  </code></pre>
  
  <p>---- end edit ----</p>