title: UI-select dropdown option not show above panel body
body: <p>I have a panel with fixed height with overflow set to auto. Inside that panel I am using ui-select.</p>
  
  <p>On-clicking/opening the select box it is getting hidden behind the panel footer and user has to scroll down to view. Is it possible to get the ui-select display outside of the box having fixed height with overflow set.</p>
  
  <pre><code>         &lt;div class="panel-body" style="height:100px;overflow:auto;"&gt;
                &lt;div class="col-md-12"&gt;
                  &lt;ui-select ng-model="person.selected" theme="select2" ng-disabled="disabled" style="min-width: 300px;"&gt;
                  &lt;ui-select-match placeholder="Select a person in the list or search his name/age..."&gt;{{$select.selected.name}}&lt;/ui-select-match&gt;
                  &lt;ui-select-choices repeat="person in people | propsFilter: {name: $select.search, age: $select.search}"&gt;
                  &lt;div ng-bind-html="person.name | highlight: $select.search"&gt;&lt;/div&gt;
                    &lt;small&gt;             email: {{person.email}}             age:             
                       &lt;span ng-bind-html="''+person.age | highlight: $select.search"&gt;&lt;/span&gt;
                    &lt;/small&gt;
                &lt;/ui-select-choices&gt;
                &lt;/ui-select&gt;
          &lt;/div&gt;
  </code></pre>
  
  <p><a href="http://plnkr.co/edit/elvnwneP0Z7avTAXDkbN?p=preview" rel="noreferrer">PLUNKER LINK</a></p>