ability to close and restore streamin server

lib/server.js

@@ -12,11 +12,16 @@ function Server (torrent, opts = {}) {
   const sockets = []
   const pendingReady = []
   let closed = false
+  const _listen = server.listen
+  const _close = server.close
 
-  server.on('connection', onConnection)
-  server.on('request', onRequest)
+  server.listen = port => {
+    closed = false
+    server.on('connection', onConnection)
+    server.on('request', onRequest)
+    _listen.call(server, port)
+  }
 
-  const _close = server.close
   server.close = cb => {
     closed = true
     server.removeListener('connection', onConnection)
@@ -25,7 +30,6 @@ function Server (torrent, opts = {}) {
       const onReady = pendingReady.pop()
       torrent.removeListener('ready', onReady)
     }
-    torrent = null
     _close.call(server, cb)
   }