feat(limit): Change multi-select limit attr (#1632)

attr.limit should be an observable property so that it is
updatable after initialization

src/uiSelectDirective.js

@@ -60,9 +60,6 @@ uis.directive('uiSelect',
         $select.onSelectCallback = $parse(attrs.onSelect);
         $select.onRemoveCallback = $parse(attrs.onRemove);
 
-        //Limit the number of selections allowed
-        $select.limit = (angular.isDefined(attrs.limit)) ? parseInt(attrs.limit, 10) : undefined;
-
         //Set reference to ngModel from uiSelectCtrl
         $select.ngModel = ngModel;
 
@@ -86,6 +83,11 @@ uis.directive('uiSelect',
             var sortable = scope.$eval(attrs.sortable);
             $select.sortable = sortable !== undefined ? sortable : uiSelectConfig.sortable;
         });
+
+        attrs.$observe('limit', function() {
+          //Limit the number of selections allowed
+          $select.limit = (angular.isDefined(attrs.limit)) ? parseInt(attrs.limit, 10) : undefined;
+        });
 
         scope.$watch('removeSelected', function() {
             var removeSelected = scope.$eval(attrs.removeSelected);