Bug 152828 Add the projectFolder property on module
When user doesn't set the resource folder path in designer, there should be a default working path for Birt to manage the report design and find the related resources. A new property should be added on Module: name: projectFolder type:URL This property only can be given from the open design method from session but should not be set after the module initialized. Concern about the backward compatiblity issue, a new method will be added. Open design with a config argument.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/ModuleHandle.java
*             if the input unit is not one of allowed.
	 * 
	 * @see org.eclipse.birt.report.model.api.metadata.DimensionValue
	 */
	public void setDefaultUnits( String units ) throws SemanticException
	{
		setStringProperty( UNITS_PROP, units );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.api.DesignElementHandle#getElement()
	 */
	public DesignElement getElement( )
	{
		return module;
	}
	/**
	 * Finds the handle to an element by a given element ID. Returns
	 * <code>null</code> if the ID is not valid, or if this session does not
	 * use IDs.
	 * 
	 * @param id
	 *            ID of the element to find
	 * @return A handle to the element, or <code>null</code> if the element
	 *         was not found or this session does not use IDs.
	 */
	public DesignElementHandle getElementByID( long id )
	{
		DesignElement element = module.getElementByID( id );