Add startup time to log messages

proxy/src/main/java/com/velocitypowered/proxy/Velocity.java

@@ -4,9 +4,15 @@ import com.velocitypowered.proxy.console.VelocityConsole;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.Locale;
+
 public class Velocity {
     private static final Logger logger = LogManager.getLogger(Velocity.class);
 
+    private static long startTime;
+
     static {
         // We use BufferedImage for favicons, and on macOS this puts the Java application in the dock. How inconvenient.
         // Force AWT to work with its head chopped off.
@@ -14,12 +20,15 @@ public class Velocity {
     }
 
     public static void main(String... args) {
+        startTime = System.currentTimeMillis();
         logger.info("Booting up Velocity...");
 
         final VelocityServer server = VelocityServer.getServer();
         server.start();
 
         Runtime.getRuntime().addShutdownHook(new Thread(server::shutdown, "Shutdown thread"));
+
+        logger.info("Done ({}s)!", new SimpleDateFormat("ss.S", Locale.getDefault()).format(new Date(System.currentTimeMillis() - startTime)));
         new VelocityConsole(server).start();
     }
 }