Print message on startup before loading log4j

Log4j takes a long time to load on startup. Before it loads, the server
appears to have frozen as there is no output until after. We now print
a loading message before this happens to let the user know the server
is actually working.

By: Travis Watkins <amaranth@ubuntu.com>

paper-server/src/main/java/org/bukkit/craftbukkit/Main.java

@@ -149,6 +149,7 @@ public class Main {
                     useConsole = false;
                 }
 
+                System.out.println("Loading libraries, please wait...");
                 MinecraftServer.main(options);
             } catch (Throwable t) {
                 t.printStackTrace();