ui: add simple dashboard

just a starting point, code ported initially over from PMG, some
minor things are handled differently though, we have not multiple
nodes (for now) so it's very 'localhost' centric.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

www/NavigationTree.js

@@ -6,6 +6,12 @@ Ext.define('PBS.store.NavigationStore', {
     root: {
 	expanded: true,
 	children: [
+	    {
+		text: gettext('Dashboard'),
+		iconCls: 'fa fa-tachometer',
+		path: 'pbsDashboard',
+		leaf: true
+	    },
 	    {
 		text: gettext('Configuration'),
 		iconCls: 'fa fa-gears',