UI files: Do not polute the global Ui namespace

Make sure all ui-files are in the plugin's internal namespace.

Change-Id: Ifb2c3093441e8feb89e46f52fbb386fc316cfd13
Reviewed-by: hjk <qthjk@ovi.com>

src/plugins/vcsbase/cleandialog.cpp

@@ -137,7 +137,7 @@ void CleanFilesTask::run()
 struct CleanDialogPrivate {
     CleanDialogPrivate();
 
-    Ui::CleanDialog ui;
+    Internal::Ui::CleanDialog ui;
     QStandardItemModel *m_filesModel;
     QString m_workingDirectory;
 };