fix: log4js migration

Author: gozeon

lib/proxy.js

@@ -39,13 +39,14 @@ exports.powerup = function(opts) {
     path: opts.storage, ttl: opts.ttl, friendlyNames: opts.friendlyNames
   });
 
-  this.log = log4js.getLogger('proxy');
-  this.log.level = (opts.verbose ? 'debug' : 'info');
-
   if (opts.logPath) {
-    log4js.loadAppender('file');
-    log4js.addAppender(log4js.appenders.file(opts.logPath), 'proxy');
+    log4js.configure({
+      appenders: { 'proxy': { type: 'file', filename: opts.logPath } },
+      categories: { default: { appenders: ['proxy'], level: opts.verbose ? 'debug' : 'info' }}
+    });
   }
+  
+  this.log = log4js.getLogger('proxy');
 
   // Fake https server aka MITM
   const mitm = https.createServer(options, exports.httpHandler);