fix(lib): File Transports Not Emitting Errors On Stream Errors

In this commit file & daily-rotate-file add an 'error' event listener on
their stream so that we can emit those errors from the transport.

fixes winstonjs#511

lib/winston/transports/daily-rotate-file.js

@@ -53,6 +53,9 @@ var DailyRotateFile = exports.DailyRotateFile = function (options) {
   else if (options.stream) {
     throwIf('stream', 'filename', 'maxsize');
     this._stream = options.stream;
+    this._stream.on('error', function(error){
+      self.emit('error', error);
+    });
 
     //
     // We need to listen for drain events when
@@ -463,6 +466,9 @@ DailyRotateFile.prototype._createStream = function () {
       self._size = size;
       self.filename = target;
       self._stream = fs.createWriteStream(fullname, self.options);
+      self._stream.on('error', function(error){
+        self.emit('error', error);
+      });
 
       //
       // We need to listen for drain events when

lib/winston/transports/file.js

@@ -56,6 +56,9 @@ var File = exports.File = function (options) {
     throwIf('stream', 'filename', 'maxsize');
     this._stream = options.stream;
     this._isStreams2 = isWritable(this._stream);
+    this._stream.on('error', function(error){
+      self.emit('error', error);
+    });
     //
     // We need to listen for drain events when
     // write() returns false. This can make node
@@ -451,6 +454,9 @@ File.prototype._createStream = function () {
       self.filename = target;
       self._stream = fs.createWriteStream(fullname, self.options);
       self._isStreams2 = isWritable(self._stream);
+      self._stream.on('error', function(error){
+        self.emit('error', error);
+      });
       //
       // We need to listen for drain events when
       // write() returns false. This can make node