fix: set correct headers

Author: DiegoRBaquero

server.js

@@ -249,9 +249,10 @@ class Server extends EventEmitter {
           }
 
           if (req.url === '/stats.json' || req.headers.accept === 'application/json') {
-            res.write(JSON.stringify(stats))
-            res.end()
+            res.setHeader('Content-Type', 'application/json')
+            res.end(JSON.stringify(stats))
           } else if (req.url === '/stats') {
+            res.setHeader('Content-Type', 'text/html');
             res.end(`
               <h1>${stats.torrents} torrents (${stats.activeTorrents} active)</h1>
               <h2>Connected Peers: ${stats.peersAll}</h2>