title: Preselected ng-select value issue
body: <p>I'm trying to get a preselected value within , i've tried multiple tutorials and looked for answers here but none worked.
  Here's the deal -> <br> 
  I load my shifts with $http.get("api/shifts"), then:</p>
  
  <pre><code> &lt;select multiple class="form-control" ng-options="shift as shift.nom for shift in shifts" ng-model="selectedShift"&gt;&lt;/select&gt;
  </code></pre>
  
  <p>And it goes to a modal window. But before this modal window opens, I can preselect a shift (to see who would be able to do it). In this case, I have</p>
  
  <pre><code> if(preselectedShift){
    $http.get("api/shifts/"+preselectedShift._id).success(function(shift){
      $scope.selectedShift = shift; //so it's replacing the ng-model in &lt;select&gt;
    })
  }
  </code></pre>
  
  <p>And all shifts appear as they should, but gives me no preselected shift. I also tried with a loop. </p>
  
  <pre><code>for (shifts.length) -&gt; if(shift[i]._id == preselectedShift._id) -&gt;$scope.selectedShift = shift[i]
  </code></pre>
  
  <p>Which gave me an error "value.forEach is not a function"</p>
  
  <p>Nor ng-select="shift._id == preselectedShift._id" has worked (gives the same error).</p>
  
  <p>Thank you in advance!</p>