Fix _findApproxDupe tagging when using a primitive property binding on iuSelectMultiple directive.

A bug was caused when _findApproxDupe was trying to set "isTag" property
on a privitive value (e.g. String). These types of values are received
when $select.selected holds an array of privitive values (using key binding).

Author: christopher-ramirez

src/uiSelectMultipleDirective.js

@@ -383,9 +383,11 @@ uis.directive('uiSelectMultiple', ['uiSelectMinErr','$timeout', function(uiSelec
             // handle the object tagging implementation
             } else {
               var mockObj = tempArr[i];
-              mockObj.isTag = true;
+              if (angular.isObject(mockObj) {
+                mockObj.isTag = true;
+              }
               if ( angular.equals(mockObj, needle) ) {
-              dupeIndex = i;
+                dupeIndex = i;
               }
             }
           }