Bug 130492 Provide a method to serialize the report with library information.
Currently, when engine generate the report document file, the document does not contain any library information. That will cause many propblem on server side. Model should provide a method to serialize the report with library information to a stream so that the generated report document can contain all information that the report need.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
* then the property is "unset."
	 * <p>
	 * Part of: Property value system.
	 * 
	 * @param propName
	 *            The name of the property to set. Must be valid. Can be a
	 *            system-defined or user-defined property name.
	 * @param value
	 *            The value to set. Must be valid for the property.
	 */
	public void setProperty( String propName, Object value )
	{
		ElementPropertyDefn prop = getPropertyDefn( propName );
		
		
		assert prop != null;
		setProperty( prop, value );
	}
	/**
	 * Sets the value of a property. The value must have already been validated,
	 * and must be of the correct type for the property. The property must be
	 * valid for this object. The property can be a system or user-defined
	 * property. The value is set locally. If the value is null, then the
	 * property is "unset."
	 * <p>
	 * Part of: Property value system.
	 * 
	 * @param prop
	 *            The property definition. Must be valid. Can be a
	 *            system-defined or user-defined property.