Make it possible to run the widgetsgallery from qmlscene

Adds a new entry point to the widgets gallery so we can test it
from qmlscene.
It's a valid use case for the components and the best tool we
have for testing that we didn't break components.

REVIEW: 119322

examples/applets/widgetgallery/contents/ui/Buttons.qml

@@ -64,7 +64,7 @@ PlasmaComponents.Page {
 
                     onClicked: {
                         console.log("Clicked");
-                        pageStack.push(Qt.createComponent(plasmoid.file("ui", "Scrollers.qml")))
+                        pageStack.push(Qt.createComponent("Scrollers.qml"))
                     }
 
                     Keys.onTabPressed: bt2.forceActiveFocus();

examples/applets/widgetgallery/contents/ui/Menu.qml

@@ -69,7 +69,7 @@ Page {
                     text: title
                 }
             }
-            onClicked: pageStack.push(Qt.createComponent(plasmoid.file("ui", page)))
+            onClicked: pageStack.push(Qt.createComponent(page))
         }
     }
     ScrollBar {

examples/applets/widgetgallery/contents/ui/standalonemain.qml

@@ -0,0 +1,56 @@
+/*
+ *   Copyright (C) 2011 by Daker Fernandes Pinheiro <dakerfp@gmail.com>
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU Library General Public License as
+ *   published by the Free Software Foundation; either version 2, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details
+ *
+ *   You should have received a copy of the GNU Library General Public
+ *   License along with this program; if not, write to the
+ *   Free Software Foundation, Inc.,
+ *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+import QtQuick 2.0
+import QtQuick.Layouts 1.1
+import org.kde.plasma.core 2.0
+import org.kde.plasma.components 2.0
+
+FrameSvgItem {
+    width: 300
+    height: 400
+    imagePath: "widgets/background"
+
+
+    ToolBar {
+        id: toolBar
+        z: 10
+
+        anchors {
+            top: parent.top
+            left: parent.left
+            right: parent.right
+            margins: 10
+        }
+    }
+
+    PageStack {
+        id: pageStack
+        toolBar: toolBar
+        clip: true
+        anchors {
+            top: toolBar.bottom
+            left: parent.left
+            right: parent.right
+            bottom: parent.bottom
+            margins: 10
+        }
+        initialPage: Qt.createComponent("Menu.qml")
+    }
+}