hide the cancel task button

we considered putting it in the progress bar, but we don't want to
encourage it's use

src/views/app.html

@@ -774,7 +774,8 @@
             <p ng-show="app.error">An error occurred during the <b>{{ app.error.installationState | taskName }}</b> operation: <span class="text-danger"><b>{{ app.error.reason + ': ' + app.error.message }}</b></span></p>
             <button class="btn btn-success pull-right" ng-click="repair.confirm()" ng-disabled="app.taskId">Retry {{ app.error.installationState | taskName }}</button>
 
-            <button class="btn btn-danger pull-right" ng-click="repair.stopAppTask(app.taskId)" ng-show="app.taskId">Cancel Current Task</button>
+            <!-- this is hidden for now, use the CLI instead -->
+            <button class="btn btn-danger pull-right" ng-click="repair.stopAppTask(app.taskId)" ng-show="false && app.taskId">Cancel Current Task</button>
           </div>
         </div>
       </div>