Improvized dashboard sorting

public/app/features/playlist/partials/playlist.html

@@ -87,10 +87,10 @@
             {{dashboard.title}}
           </td>
           <td style="text-align: right">
-            <button class="btn btn-inverse btn-mini" ng-click="moveDashboardUp(dashboard)">
+            <button class="btn btn-inverse btn-mini" ng-hide="$first" ng-click="moveDashboardUp(dashboard)">
               <i class="fa fa-arrow-up"></i>
             </button>
-            <button class="btn btn-inverse btn-mini" ng-click="moveDashboardDown(dashboard)">
+            <button class="btn btn-inverse btn-mini" ng-hide="$last" ng-click="moveDashboardDown(dashboard)">
               <i class="fa fa-arrow-down"></i>
             </button>
             <button class="btn btn-inverse btn-mini" ng-click="removeDashboard(dashboard)">