Bug 181365 There is no icon in the background image of MasterPage property editor
Description: In the property editor of Masterpage, go to advanced tab. Click Background node to set the "background image", but there is no icon to invoke the image resources in the local machine. In style builder, there is a "Browse.." button to set the background image. That will be more convient for user to set background image.
UI/org.eclipse.birt.report.designer.ui.views/src/org/eclipse/birt/report/designer/internal/ui/views/attributes/widget/PropertyEditorFactory.java
{
	private static PropertyEditorFactory instance = new PropertyEditorFactory( );
	private static String booleanValues[] = new String[]{
			"false", "true"}; 
	/**
	 * Avoid instantiation.
	 */
	private PropertyEditorFactory( )
	{
	}
	/**
	 * Gets the single instance of this class.
	 * 
	 * @return instance
	 */
	public static PropertyEditorFactory getInstance( )
	{
		return instance;
	}
	public CellEditor createPropertyEditor( Composite parent, Object o )
	{
		
		CellEditor editor = null;
		String[] unitsList = null;
		GroupPropertyHandleProvider handle = GroupPropertyHandleProvider.getInstance( );
		
		if ( handle.isReadOnly( o ) )
		{
			return null;