reset self.peers = {} after destroy

Supersedes PR webtorrent#135

Author: feross

lib/client/websocket-tracker.js

@@ -137,6 +137,8 @@ WebSocketTracker.prototype._openSocket = function () {
   var self = this
   self.destroyed = false
 
+  if (!self.peers) self.peers = {}
+
   self._onSocketConnectBound = self._onSocketConnect.bind(self)
   self._onSocketErrorBound = self._onSocketError.bind(self)
   self._onSocketDataBound = self._onSocketData.bind(self)