Bug 124067 When select the XML file, the relative path should be supported.
Description: When select the XML file, the relative path should be supported. Step to reproduce: 1. new a report 2. new a datasource and dataset based on a XML file 3. select the XML file, the file relative path should be used. Actual result: only the absolute path is supported. Expect result: the relative and absolute path are supported.
data/org.eclipse.birt.report.data.oda.xml/src/org/eclipse/birt/report/data/oda/xml/util/ui/SchemaPopulationUtil.java
* 
	 * @param fileName
	 * @return
	 * @throws OdaException
	 * @throws MalformedURLException 
	 * @throws URISyntaxException 
	 */
	public static ATreeNode getSchemaTree( String fileName, boolean incAttr )
			throws OdaException, MalformedURLException, URISyntaxException
	{
		includeAttribute = incAttr;
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance( );
		factory.setNamespaceAware( true );
		URI uri = null;
		File f = new File(fileName);
		uri = f.toURI(); 
		
		
		if ( uri == null )
		{
			uri = new URI( fileName );
		}
		
		XSLoader xsLoader = new XMLSchemaLoader( );
		XSModel xsModel = xsLoader.loadURI( uri.toString( ) );
		ATreeNode complexTypesRoot = populateComplexTypeTree( xsModel );
		XSNamedMap map = xsModel.getComponents( XSConstants.ELEMENT_DECLARATION );
		ATreeNode root = new ATreeNode( );
		root.setValue( "ROOT" );
		for ( int i = 0; i < map.getLength( ); i++ )