Refactor readFile to match nodejs File System native interface

lib/smb2.js

@@ -183,11 +183,16 @@ proto.readdir = function(path, cb){
  *  - close the file
  *
  */
-proto.readFile = function(path, cb){
+proto.readFile = function(filename, options, cb){
   var connection = this;
 
+  if(typeof options == 'function'){
+    cb = options;
+    options = {};
+  }
+
   // SMB2 open file
-  SMB2Request('open', {path:dest}, connection, function(err, file){
+  SMB2Request('open', {path:filename}, connection, function(err, file){
     if(err) cb && cb(err);
     // SMB2 read file content
     else {
@@ -222,7 +227,7 @@ proto.readFile = function(path, cb){
         createPackets();
         if(nbRemainingPackets==0 && offset.ge(fileLength)) {
           SMB2Request('close', file, connection, function(err){
-            cb && cb(err, result);
+            cb && cb(err, result.toString());
           })
         }
       }