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
* @return the custom defined color that matches, or <code>null</code> if
	 *         the color name was not found in the custom color palette.
	 */
	public CustomColor findColor( String colorName )
	{
		StructureDefn defn = (StructureDefn) MetaDataDictionary.getInstance( )
				.getStructure( CustomColor.CUSTOM_COLOR_STRUCT );
		return (CustomColor) StructureRefUtil.findStructure( this, defn,
				colorName );
	}
	/**
	 * Finds a config variable by name
	 * 
	 * @param variableName
	 *            the configure variable name
	 * @return the config variable that matches, or <code>null</code> if the
	 *         variable name was not found.
	 */
	public ConfigVariable findConfigVariabel( String variableName )
	{
		StructureDefn defn = (StructureDefn) MetaDataDictionary.getInstance( )
				.getStructure( ConfigVariable.CONFIG_VAR_STRUCT );
		return (ConfigVariable) StructureRefUtil.findStructure( this, defn,
				variableName );
	}
	/**
	 * Finds an embedded image by name.
	 * 
	 * @param imageName
	 *            the embedded image name