Don't restrict EventBus registration to init phase

After the logging stuff added in 8692ca17d13eda036b5ef996ec8e8706e7707d80, we weren't able to register stuff into the eventbus after the game is started. This is needed for some things. I, for example, give each world some helper objects which track some statistics and listen to events. This won't work after said commit. Same for things the ForgeEssentials guys are planning with their module loading system. When they aren't able to add things to the eventbus when the game is started, that entire plan won't work.