Bug 197228 Need updaet createdBy info when serialize the module
When open module, designer will pass the property map which contains the createdBy info. this info should be retained by moduleHandle and then be updated and written when doing serialization. Note if this info is null, model should not update it during serialization. This could happen for api users or third-party designer. For BIRT designer, it will guarantee this value always not null.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/Module.java
*            the library to insert
	 */
	public void addLibrary( Library library )
	{
		if ( libraries == null )
			libraries = new ArrayList( );
		libraries.add( library );
	}
	/**
	 * Drops the given library from library list.
	 * 
	 * @param library
	 *            the library to drop
	 * @return the position of the library to drop
	 */
	public int dropLibrary( Library library )
	{
		assert libraries != null;
		assert libraries.contains( library );
		int posn = libraries.indexOf( library );
		libraries.remove( library );
		return posn;
	}
	/**
	 * Returns the module with the given namespace. This method checks the
	 * namespace in both directly and indirectly included libraries.
	 * 
	 * @param namespace
	 *            the module namespace
	 * @return the module with the given namespace