Add server-id fetch and /serverid command

src/main/java/com/imaginarycode/minecraft/redisbungee/RedisBungee.java

@@ -208,6 +208,7 @@ public final class RedisBungee extends Plugin implements Listener {
             getProxy().getPluginManager().registerCommand(this, new RedisBungeeCommands.LastSeenCommand());
             getProxy().getPluginManager().registerCommand(this, new RedisBungeeCommands.IpCommand());
             getProxy().getPluginManager().registerCommand(this, new RedisBungeeCommands.SendToAll());
+            getProxy().getPluginManager().registerCommand(this, new RedisBungeeCommands.ServerId());
             getProxy().getPluginManager().registerListener(this, this);
             api = new RedisBungeeAPI(this);
             psl = new PubSubListener();

src/main/java/com/imaginarycode/minecraft/redisbungee/RedisBungeeAPI.java

@@ -120,4 +120,12 @@ public class RedisBungeeAPI {
     public final void sendProxyCommand(@NonNull String proxyId, @NonNull String command) {
         plugin.sendProxyCommand(proxyId, command);
     }
+
+    /**
+     * Get the current BungeeCord server ID for this server.
+     * @return the current server ID
+     */
+    public final String getServerId() {
+        return RedisBungee.getConfiguration().getString("server-id");
+    }
 }

src/main/java/com/imaginarycode/minecraft/redisbungee/RedisBungeeCommands.java

@@ -165,4 +165,18 @@ class RedisBungeeCommands {
             }
         }
     }
+
+    public static class ServerId extends Command {
+        ServerId() {
+            super("serverid", "redisbungee.command.serverid");
+        }
+
+        @Override
+        public void execute(CommandSender sender, String[] args) {
+            TextComponent textComponent = new TextComponent();
+            textComponent.setText("You are on " + RedisBungee.getApi().getServerId() + ".");
+            textComponent.setColor(ChatColor.YELLOW);
+            sender.sendMessage(textComponent);
+        }
+    }
 }