add run time in version info

broker/src/main/java/io/moquette/server/Server.java

@@ -80,6 +80,7 @@ public class Server {
     }
 
     private ServerAcceptor m_acceptor;
+    private long startTime;
 
     private boolean m_shutdowning = false;
 
@@ -102,6 +103,10 @@ public class Server {
         System.out.println(BANNER);
     }
 
+    public Server() {
+        startTime = System.currentTimeMillis();
+    }
+
     public static void start(String[] args) throws IOException {
         instance = new Server();
         final IConfig config = defaultConfig();
@@ -513,4 +518,7 @@ public class Server {
     public ThreadPoolExecutorWrapper getCallbackScheduler() {
         return callbackScheduler;
     }
+    public long getRunTime() {
+        return (System.currentTimeMillis() - startTime)/1000;
+    }
 }