core: rename uniqueidmanager.{cpp,h} as the class UniqueIdManager is gone

Change-Id: Iffe04bc3bb0103cbac605f0734bbfd66eb7fd854
Reviewed-on: http://codereview.qt.nokia.com/4215
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: hjk <qthjk@ovi.com>

src/plugins/coreplugin/mainwindow.cpp

@@ -64,7 +64,7 @@
 #include "variablemanager.h"
 #include "versiondialog.h"
 #include "statusbarmanager.h"
-#include "uniqueidmanager.h"
+#include "id.h"
 #include "manhattanstyle.h"
 #include "navigationwidget.h"
 #include "rightpane.h"