<div class="input-group">
  <span class="input-group-btn">
    <button class="btn btn-default" type="button" ng-click="open($event)" ng-disabled="disabled"><i class="fa fa-calendar"></i></button>
  </span>
  <input type="text" placeholder="Select a date..." class="form-control" ng-disabled="disabled">
</div>

<div class="input-group">
  <span class="input-group-addon add-on" ng-click="open($event)">
    <i class="fa fa-calendar"></i>
  </span>
  <input type="text" placeholder="Select a date..." class="form-control" ng-disabled="disabled">
</div>

Make calendar icon match previouse date picker
Make calendar icon match previouse date picker
