The resources of language packs are not recognised when uploaded through the plugin interface

Language packs can now be loaded by dropping the JAR in the WEB-INF/lib/ directory. However, uploading the same JAR through the "Manage Plugins" interface and switching to that language does not work. It seems that the ResourceBundle class (in the JDK) can't find the .properties files for the plugin.

I suspect this is a class-loading issue, and we will have to hack around so that the plugin class-loader is used instead of the default one.

WORKAROUND: Place language pack JARs in the WEB-INF/lib/ directory.