* Initial grouping of messages_en.yml (thanks to input by @Twonox)
* Change MessageFileVerifier to only do verification - no writing
* Create classes for sorting and grouping messages as per the messages_en file
- Don't scan for translations on initialization in TranslationPageGenerator in order to speed up startup time of ToolsRunner
- Extract checking for null / empty array of File#listFiles into a separate method
- Move single method of RuntimeUtils into Utils class
- To check a single file just enter the language file, e.g. "es"
- Pass File object to MessageFileVerifier instead of String path that will be constructed to a File again...
- Make verification task add todo comments to YML files in the same order as the MessageKey enum
- Use DefaultCharsets everywhere instead of Guava's Charsets class (thanks to DNx5)
- Classes still won't be present in JAR but classes will be automatically compiled by Maven inside of the test scope, facilitating the execution of tool tasks
