Add support for BukkitForge using 'overworld' as the main world name.

EssentialsGroupManager/src/Changelog.txt

@@ -209,3 +209,4 @@ v 2.0:
 	- Synchronize pushing to Bukkit perms to prevent any ConcurrentModificationException.
 	- Do not grant any permissions (nor update Bukkit) if the server is in offline mode and the player has the permission node 'groupmanager.noofflineperms'.
 	- Negate 'groupmanager.noofflineperms' by default in the owner group.
+	- Add support for BukkitForge using 'overworld' as the main world name.

EssentialsGroupManager/src/org/anjocaido/groupmanager/dataholder/worlds/WorldsHolder.java

@@ -477,14 +477,22 @@ public class WorldsHolder {
 
 	private void verifyFirstRun() {
 
+		/* Do not use the folder name if this 
+		 * is a Bukkit Forge server.
+		 */
+		if (plugin.getServer().getName().equalsIgnoreCase("BukkitForge")) {
+			serverDefaultWorldName = "overworld";
+
+		} else {
 			Properties server = new Properties();
 			try {
 				server.load(new FileInputStream(new File("server.properties")));
 				serverDefaultWorldName = server.getProperty("level-name").toLowerCase();
-			setupWorldFolder(serverDefaultWorldName);
 			} catch (IOException ex) {
 				GroupManager.logger.log(Level.SEVERE, null, ex);
 			}
+		}
+		setupWorldFolder(serverDefaultWorldName);
 
 	}