[partition] Fix user-visible strings

- The default window title in the designer file wasn't a good string
   to translate. Use one of the titles instanced from elsewhere.
 - The window titles set in subclasses were not translatable.

FIXES #1092

src/modules/partition/gui/CreateVolumeGroupDialog.cpp

@@ -34,7 +34,7 @@ CreateVolumeGroupDialog::CreateVolumeGroupDialog( QString& vgName,
     , m_selectedPVs( selectedPVs )
     , m_peSize( pSize )
 {
-    setWindowTitle( "Create Volume Group" );
+    setWindowTitle( tr( "Create Volume Group" ) );
 
     peSize()->setValue( pSize );
 

src/modules/partition/gui/ResizeVolumeGroupDialog.cpp

@@ -35,7 +35,7 @@ ResizeVolumeGroupDialog::ResizeVolumeGroupDialog( LvmDevice *device,
     : VolumeGroupBaseDialog( device->name(), device->physicalVolumes(), parent )
     , m_selectedPVs( selectedPVs )
 {
-    setWindowTitle( "Resize Volume Group" );
+    setWindowTitle( tr( "Resize Volume Group" ) );
 
     for ( int i = 0; i < pvList()->count(); i++ )
         pvList()->item(i)->setCheckState( Qt::Checked );

src/modules/partition/gui/VolumeGroupBaseDialog.ui

@@ -11,7 +11,7 @@
    </rect>
   </property>
   <property name="windowTitle">
-   <string>VolumeGroupDialog</string>
+   <string>Create Volume Group</string>
   </property>
   <layout class="QGridLayout" name="gridLayout">
    <item row="0" column="0">