fix: http announce no left (webtorrent#548)

* fix: http announce no left

* fix: proper left check

Author: ThaUnknown

lib/client/http-tracker.js

@@ -55,6 +55,8 @@ class HTTPTracker extends Tracker {
       peer_id: this.client._peerIdBinary,
       port: this.client._port
     })
+
+    if (params.left !== 0 && !params.left) params.left = 16384
     if (this._trackerId) params.trackerid = this._trackerId
 
     this._request(this.announceUrl, params, (err, data) => {