Fix creation and import Exploit (#2353)

Through this fix you can avoid deleting of important folders.

src/main/java/com/onarandombox/MultiverseCore/commands/CreateCommand.java

@@ -47,9 +47,14 @@ public class CreateCommand extends MultiverseCommand {
         this.worldManager = this.plugin.getMVWorldManager();
     }
 	
+	private String trimWorldName(String userInput) {
+        // Removes relative paths.
+        return userInput.replaceAll("^[./\\\\]+", "");
+    }
+	
     @Override
     public void runCommand(CommandSender sender, List<String> args) {
-        String worldName = args.get(0);
+        String worldName = trimWorldName(args.get(0));
         File worldFile = new File(this.plugin.getServer().getWorldContainer(), worldName);
         String env = args.get(1);
         String seed = CommandHandler.getFlag("-s", args);
@@ -67,6 +72,12 @@ public class CreateCommand extends MultiverseCommand {
             }
         }
 		
+		// Make sure the world name doesn't contain the words 'plugins' and '.dat'
+		if(worldName.contains("plugins")||worldName.contains(".dat")){
+			sender.sendMessage(ChatColor.RED + "Multiverse cannot create a world that contains 'plugins' or '.dat'");
+            return;
+		}
+		
         if (this.worldManager.isMVWorld(worldName)) {
             sender.sendMessage(ChatColor.RED + "Multiverse cannot create " + ChatColor.GOLD + ChatColor.UNDERLINE
                     + "another" + ChatColor.RESET + ChatColor.RED + " world named " + worldName);

src/main/java/com/onarandombox/MultiverseCore/commands/ImportCommand.java

@@ -82,6 +82,12 @@ public class ImportCommand extends MultiverseCommand {
             return;
         }
 		
+		// Make sure the world name doesn't contain the words 'plugins' and '.dat'
+		if(worldName.contains("plugins")||worldName.contains(".dat")){
+			sender.sendMessage(ChatColor.RED + "Multiverse cannot create a world that contains 'plugins' or '.dat'");
+            return;
+		}
+
         // Make sure we don't already know about this world.
         if (this.worldManager.isMVWorld(worldName)) {
             sender.sendMessage(ChatColor.GREEN + "Multiverse" + ChatColor.WHITE