Updated CommandManager to be compatible with PWP

EchoPet should be compatible with PWP again. (The way I handle this now is not really safe, as it not checks wheter or not there is a commandMap field so if another (crappy) plugin injects it's own PluginManager in the server and doesn't add this map/renames it, it will start spitting out NullPointerExceptions, that's when we start using our backup-command-handler.)