Allow to explicitly exclude languages from processing

By adding the language code prefixed with an exclamation mark, it is possible to exclude the given language from the processing. This is active for all tools which use the ConfigUtils.parseLanguages method for retrieving the set of relevant languages (e.g., importing the Wikipedia dumps).

Example:
the arguments "10000-,!en,!de" would lead to processing of all languages with at least 10000 articles except for the English and the German Wikipedia.