Correct or clarify documentation on setting Preferences Framework localization

The documentation at http://docs.fluidproject.org/infusion/development/LocalizationInThePreferencesFramework.html#specifying-a-localization is either incorrect or unclear - when implementing https://github.com/waharnum/uio-multilingual/blob/master/demos/src/js/UIOMultilingualDemo.js#L41 the obvious syntax as described did not appear to work, and it was necessary to address the messageLoader subcomponent directly.

At minimum, the documentation needs to be clarified, and it needs to be investigated as to whether this is in fact working as described - the 'settings' object described is constructed by an expander at https://github.com/fluid-project/infusion/blob/0ca2eac0a06731f99588399c9abd3e9d29732235/src/framework/preferences/js/PrefsEditor.js#L35, and it is unclear where or how the locale should be configured.

At a more fundamental level, it seems assymetrical to set the defaultLocale on the component options directly (https://github.com/fluid-project/infusion/blob/0ca2eac0a06731f99588399c9abd3e9d29732235/src/framework/preferences/js/PrefsEditor.js#L33) but require a more complicated mechanism for setting the locale - however, I may lack history or context for this decision.