FIX: Fix duplicate options in ng-options

Under angular.js:26629 in the updateOptions function, the
currentElement variable will be assigned to the generated
comment of the ng-if (i.e., <!-- ngIf: !isTaskDefMode -->)
and not the select <option> element.

This is a bug with angular by having a first, default option
in a select with ng-options -- it *must not* have an ng-if
clause on it or duplicate entries are added.

src/app/units/states/tasks/inbox/directives/task-list/task-list.tpl.html

@@ -19,7 +19,7 @@
           ng-change="taskDefinitionIdChanged()"
           autofocus="{{autofocus.onTaskDefinitionSelect}}"
           class="form-control input-md">
-          <option value="" ng-if="!isTaskDefMode">All task definitions</option>
+          <option value="" ng-hide="!isTaskDefMode">All task definitions</option>
         </select>
       </div>
       <p class="help-block">You can choose to display submissions of a specific task definition here.</p>