Add small indicator if no users have been found

src/views/users.html

@@ -313,6 +313,9 @@
                 </tr>
               </thead>
               <tbody>
+                <tr ng-show="users.length === 0">
+                  <td colspan="5" class="text-center text-muted">No users found</td>
+                </tr>
                 <tr ng-repeat="user in users" ng-class="{'text-muted': !user.active}">
                   <td>
                     <i class="fa fa-briefcase arrow" ng-show="user.active && user.admin" uib-tooltip="This user can manage apps, groups and other users"></i>