Resolves #224 Main UI tablet support

lib/pages/entity.page.dart

@@ -10,9 +10,10 @@ class EntityViewPage extends StatefulWidget {
 }
 
 class _EntityViewPageState extends State<EntityViewPage> {
-  String _title;
   StreamSubscription _refreshDataSubscription;
   StreamSubscription _stateSubscription;
+  Entity entity;
+  Entity forwardToMainPage;
 
   @override
   void initState() {
@@ -26,16 +27,18 @@ class _EntityViewPageState extends State<EntityViewPage> {
     _refreshDataSubscription = eventBus.on<RefreshDataFinishedEvent>().listen((event) {
       setState(() {});
     });
-    _prepareData();
+    entity = HomeAssistant().entities.get(widget.entityId);
   }
 
-  void _prepareData() async {
-    _title = HomeAssistant().entities.get(widget.entityId).displayName;
-  }
-
-
   @override
   Widget build(BuildContext context) {
+    Widget body;
+    if (MediaQuery.of(context).size.width >= Sizes.tabletMinWidth) {
+      _popAfterBuild();
+      body = PageLoadingIndicator();
+    } else {
+      body = entity.buildEntityPageWidget(context);
+    }
     return new Scaffold(
       appBar: new AppBar(
         leading: IconButton(icon: Icon(Icons.arrow_back), onPressed: (){
@@ -43,16 +46,23 @@ class _EntityViewPageState extends State<EntityViewPage> {
         }),
         // Here we take the value from the MyHomePage object that was created by
         // the App.build method, and use it to set our appbar title.
-        title: new Text(_title),
+        title: new Text("${entity.displayName}"),
       ),
-      body: HomeAssistant().entities.get(widget.entityId).buildEntityPageWidget(context),
+      body: body,
     );
   }
 
+  _popAfterBuild() async {
+    forwardToMainPage = entity;
+    await Future.delayed(Duration(milliseconds: 300));
+    Navigator.of(context).pop();
+  }
+
   @override
   void dispose(){
     if (_stateSubscription != null) _stateSubscription.cancel();
     if (_refreshDataSubscription != null) _refreshDataSubscription.cancel();
+    eventBus.fire(ShowEntityPageEvent(entity: forwardToMainPage));
     super.dispose();
   }
 }