Add note about BungeeCord when in offline mode.

See PR #10 for motivation.

CraftBukkit-Patches/0096-Treat-Bungee-as-Online-Mode.patch

@@ -4,6 +4,26 @@ Date: Sat, 12 Apr 2014 21:23:58 +1000
 Subject: [PATCH] Treat Bungee as Online Mode
 
 
+diff --git a/src/main/java/net/minecraft/server/DedicatedServer.java b/src/main/java/net/minecraft/server/DedicatedServer.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/server/DedicatedServer.java
++++ b/src/main/java/net/minecraft/server/DedicatedServer.java
+@@ -0,0 +0,0 @@ public class DedicatedServer extends MinecraftServer implements IMinecraftServer
+             if (!this.getOnlineMode()) {
+                 DedicatedServer.LOGGER.warn("**** SERVER IS RUNNING IN OFFLINE/INSECURE MODE!");
+                 DedicatedServer.LOGGER.warn("The server will make no attempt to authenticate usernames. Beware.");
+-                DedicatedServer.LOGGER.warn("While this makes the game possible to play without internet access, it also opens up the ability for hackers to connect with any username they choose.");
++                // Spigot start
++                if (org.spigotmc.SpigotConfig.bungee) {
++                    DedicatedServer.LOGGER.warn("Whilst this makes it possible to use BungeeCord, unless access to your server is properly restricted, it also opens up the ability for hackers to connect with any username they choose.");
++                    DedicatedServer.LOGGER.warn("Please see http://www.spigotmc.org/wiki/firewall-guide/ for further information.");
++                } else {
++                    DedicatedServer.LOGGER.warn("While this makes the game possible to play without internet access, it also opens up the ability for hackers to connect with any username they choose.");
++                }
++                // Spigot end
+                 DedicatedServer.LOGGER.warn("To change this, set \"online-mode\" to \"true\" in the server.properties file.");
+             }
+ 
 diff --git a/src/main/java/net/minecraft/server/NameReferencingFileConverter.java b/src/main/java/net/minecraft/server/NameReferencingFileConverter.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
 --- a/src/main/java/net/minecraft/server/NameReferencingFileConverter.java