Merge pull request #692 from notFloran/webui-fix-alert

[WebUI] when alert is ongoing hide level

glances/outputs/static/html/plugins/alert.html

 <div class="table">
     <div class="table-row" ng-repeat="alert in statsAlert.getAlerts()">
         <div class="table-cell text-left">
-{{alert.begin | date : 'yyyy-MM-dd H:mm:ss'}} ({{ alert.ongoing ? 'ongoing' : alert.duration }}) - {{alert.level}} on <span class="{{ alert.level | lowercase }}">{{alert.name}}</span> ({{alert.max}})
+{{alert.begin | date : 'yyyy-MM-dd H:mm:ss'}} ({{ alert.ongoing ? 'ongoing' : alert.duration }}) - <span ng-hide="alert.ongoing">{{alert.level}} on</span> <span class="{{ alert.level | lowercase }}">{{alert.name}}</span> ({{alert.max}})
 		</div>
     </div>
 </div>