修复一个有可能导致下载失败的问题

Aria/src/main/java/com/arialyy/aria/util/CommonUtil.java

@@ -300,7 +300,9 @@ public class CommonUtil {
   public static Properties loadConfig(File file) {
     Properties      properties = new Properties();
     FileInputStream fis        = null;
-
+    if (!file.exists()){
+      createFile(file.getPath());
+    }
     try {
       fis = new FileInputStream(file);
       properties.load(fis);