Some common dirs missing in core_component::$ignoreddirs

The core_component::$ignoreddirs lists all directories that are reserved and cannot be used as valid plugin names. At the moment, it does not contain amd and lang.

This is a problem because we have webservice defined as both a core subsystem as well as a plugin type (for WS protocols) - and each of these point to /webservice as their root location.

As a consequence, we cannot introduce core_webservice AMD modules (webservice/amd/) or strings (webservice/lang/) because they would be considered as new WS protocols webservice_amd and webservice_lang respectively.