Bug 211004 Failed to remove temp db directory after running multiple reports
Description: I use Report Engine API to do runAndrender, run and dataextract tasks on multiple reports. Before the Platform started, I change the temp folder(System.setProperty( "java.io.tmpdir", TEMP_HOME )). Each task is closed after it finished and I shutdown the Platform after all the tasks finished. In log I found "Fail to remove one or more file in temp db directory,but it will be removed when the VM exits: D:\BIRT_NG\temp/BIRTSampleDB_1196129572031_10a6ae2". In temp folder the BIRTSampleDB_XXX is still here but not removed. I think it is the issue when remove the Temp sampleDB. Build number: 2.3.0.v20071127-0630
data/org.eclipse.birt.report.data.oda.sampledb/src/org/eclipse/birt/report/data/oda/sampledb/SampleDBJDBCConnectionFactory.java
if ( derbyClassLoader.isGood() )
		{
			ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
			if ( contextLoader != null && ! ( contextLoader instanceof ContextClassLoaderDelegator) )
			{
				
				Thread.currentThread().setContextClassLoader(
						new ContextClassLoaderDelegator( contextLoader, derbyClassLoader ) );
			}
		}
	}
	
	/**
	 * Gets a new instance of Derby JDBC Driver
	 */
	private Driver getDerbyDriver() throws SQLException
	{
		if ( derbyDriver == null )
		{
			try
			{
				derbyDriver = (Driver) Class.forName( SampleDBConstants.DERBY_DRIVER_CLASS, 
						true, derbyClassLoader ).newInstance();
			}
			catch ( Exception e)
			{
				logger.log( Level.WARNING, "Failed to load Derby embedded driver: " +
						SampleDBConstants.DERBY_DRIVER_CLASS, e );
				throw new SQLException (e.getLocalizedMessage());