Fix MinecraftForge.initialize not being called.

Fixes UsernameCache and harvest tools
Closes #5529

src/main/java/net/minecraftforge/common/ForgeMod.java

@@ -80,6 +80,7 @@ public class ForgeMod implements WorldPersistenceHooks.WorldPersistenceHook
     {
         LOGGER.info(FORGEMOD,"Forge mod loading, version {}, for MC {} with MCP {}", ForgeVersion.getVersion(), MCPVersion.getMCVersion(), MCPVersion.getMCPVersion());
         INSTANCE = this;
+        MinecraftForge.initialize();
         WorldPersistenceHooks.addHook(this);
         WorldPersistenceHooks.addHook(new FMLWorldPersistenceHook());
         final IEventBus modEventBus = FMLJavaModLoadingContext.get().getModEventBus();